In general American studios/networks are focused primarily on ratings and the income that brings. If a show underperforms even on one episode, that's enough to toss it. And I assume that even goes for shows put in front of test audiences.
It's a practice that's been going on forever, certainly since I was a little kid. I remember shows that I loved never coming back.
But it's not just on cartoons, it's pretty much any show that underperforms. Meddling on the executive level is just the norm here, and I doubt it will change.

I had the same feeling a couple years ago. If I see a cartoon being hyped up on twitter or tumblr, my first instinct is to avoid it, especially if it has a style like Korra's. If my friends personally recommend it to me or talk it up, I might consider checking it out. I've been pleasantly surprised before, but I often worry I'll come away having loved the show at first and then noticing writing issues that it feels like only I can see.

It's really unfortunate in the case of Amphibia, The Owl House, and Infinity Train, because I heard they were genuinely good but got cancelled before they could properly finish their stories.

I honestly miss self contained "wacky" comedy and character focused cartoons like Phineas and Ferb (which was kind of the last hurrah for that type of cartoon come to think of it.) Because as much as I do love a good story driven cartoon, it's honestly getting kinda old that every big cartoon needs to be Capital E EPIC nowadays. It's like the exact opposite of back in the day when everything had to be a standalone and serialized cartoons were a rarity.

At least that's my flaming hot take on the subject, anyways.

I dunno for sure if this was the case with every season, but when the show was first announced, it was supposed to be a one-season show. And then I think shortly after the finale came out, it was announced that there'd be a Season 2. Then, I think it got switched to online-only during Season 3? A couple of random episodes after that got aired on TV, but I don't know which ones. It was a mess.

I have to agree with you, especially with some of the examples you've provided. I don't think badly of any of these shows (except one), specifically because I haven't to seen LOK, Amphibia, or much of Star vs., so I can't really speak on them. And I purposely avoided watching LOK because I knew I wouldn't give it a fair shot since comparisons to ATLA would cloud my objectivity.

I think one of the biggest issues with these shows (Gravity Falls, especially Steven Universe, and ML) is their pacing. The shows were either too succinct or not succinct enough for the story. To be fair to Gravity Falls, for the most part everything was good: the characters, the mystery, the humor, and even the pacing. But towards the end, things kinda wrapped up really quickly. Like Grunkle Stan getting his memories back after every thing; I feel like they could have milked that for an episode or two more and it would have had more emotional weight. The finale as a whole, like you mentioned, was a little underwhelming. They probably could've made the situation come off more dire for the human characters. In the end, I hold nothing against the show; still a good one, and I think there was a production/network reason as to why it last 2 seasons despite being a long running show.

Steven Universe. What hasn't been said about this show? What I will say is that the show was pretty bloated and it felt like in the beginning, it wasn't sure if was going to be a slice of life or an action fantasy story. Season one spent a lot of time on the town of... Beach City (could be wrong about the name ) when for the most part, the story really wasn't going to feature those characters. If more town focused episodes played in between story arcs like filler episodes do in most shounen anime, I think they would've been better received than front loading them in season one. (If anyone ever wants to watch Steven Universe, skip the first season, I don't think you need to watch it). Season 2 is where the story really feels like it starts, but there's still a lot of waffling and resolutions to arcs that are disappointing. Like the Cluster arc ending, mad underwhelming. I can understand having some resolutions great are emotional and done with words and not swords, but can at least some battles be resolved with swords. Like, come on, it's and action show. Like the confrontation with White Diamond would have been far more fascinating if they also got to fight her, but whatever.

Miraculous... Ladybug... hah, where do I begin. Okay, the first to seasons where good. S1 was formulaic but the plot were simple and the characters are fun. S2. Little more story based, some character development, and kept the vibes of S1, good stuff. Season three, waste of fucking time, ugh. It backpedals on one character's development rendering their arc in the previous season pointless, about a 1/5 of the 26 episode season are filler, mean nothing for the plot, or will likely never come up again, they wrote out an important character even though they hadn't used up their narrative utility, they brought back a character that disappeared from the previous season and didn't use them properly, and overall the third season was unfocused and could not let go of the need to return to the status quo at the start of every episode... Oh and they made the main character a creepy, stalker-y mess so that was fun. Like I said, the show is unfocused and it doesn't know what to do with the characters to make a cohesive plot, and I'm under the impression most if not all of the problems come from the head writer/creator. I haven't seen the fourth season, I don't know if I ever will with how the quality of the show plummeted. This is the one show I actually have something against just in how it spectacularly soured my expectations. Sorry this kinda turned into a "ML is bad" rant.

I'm sure eventually a show will pop up that lives up to the expectations that the story sets up.

most of thie problems comes down to money, the network execs want to see returns on their investments, there are times when they dont get to finish the story they want to tell, and some dont end when they should have.how i see it in the case of ladybug they didnt keep charcters consistant and it kinda hurt the show some,namely marinette became really creepy stalkerish,LOK i think could have used more the format of ATLA a 20 ep run for each book,as some felt really rushed and incomplete,voltron the legendary defender 's issues comes from alot of imbalance between seasons 13 eps here another 6 there was not fun,,but all of these suffer from a need to have a non fighting or non confrontational ending, thought i do understand some problems dont need to be fought with fists, alot feels really forced when you know it cant , or wouldn't go that way

A bunch of people have mentioned money and executive/studio meddling, and I think that's part of it for sure, but something else is that a lot of american shows are trying to have their cake and eat it too: Gravity Falls was mostly self-contained episodic comedy stories with the occasional story-based moment and bits of character development sprinkled in. Same goes for Steven Universe, Star Vs. and Miraculous.

For the longest time, American cartoons were exclusively meant to be viewed episodically, with the status quo being 100% reset every single episode, because we can't expect children to follow actual storylines or, god forbid, character arcs. They're just stupid idiot babies who are staring at the pretty colors on the screen for 30 minutes. They don't think or care about the quality of the stories. They have the attention spans of goldfish until they turn 18, so the only thing worth showing them is jokes that are set up and concluded in a matter of seconds, otherwise all that effort into a story is just a waste of time and money.

Then Avatar came along and said 'fuck you I do what I want' and was the best thing ever made forever.

It's actually an incredibly difficult skill to balance episodic plotlines with serialized storytelling: Longer TV dramas and procedurals can handle it more easily (House M.D., Burn Notice, Person of Interest, The Blacklist) due to their 44 minute per episode runtime: spending 4-5 minutes advancing an overarching plot is only 10% of their total script, while a 22 minute episode of animation requires double the real-estate to advance its larger serialized narrative the same amount.
They therefore need a ton of extra care and effort put into making sure returning viewers are satisfied by the advancement of the serialized plotline, while also making sure new viewers aren't lost and can get on board with the episode's storyline without much trouble.

Again, Avatar rode that razor's edge with such flawless aplomb that it looked effortless: it seemed to the studios like they could totally just do episodic action/comedy plots that also string together into a larger overarching serialized story because hey, it worked for Avatar, right? Now a ton of shows have tried to do both at the same time and fallen flat on their face in one direction or the other. They either have boring, uninteresting filler for episodic plots that make everyone frustrated waiting for the actual narrative to happen (Steven Universe), or they have uninteresting jumbled messes for their big serialized plotlines that everyone rolls their eyes at while enjoying the simpler one-off episodic stories inbetween (Star Vs.)

I hate to be 'that weeb', but anime honestly had this figured out a long-ass time ago: the vast majority of their stories are separated into arcs that go over the course of multiple episodes, allowing for 'reset points' where new viewers can jump on when a new storyline starts, but also creating larger, more satisfying conclusions for each storyline by stringing anywhere from 2 to 100 episodes together. Avatar did a great job of adapting this formula into the more rigidly episodic format of western cartoons, but I don't think anyone realized just how damn good of a job it was doing at something that is deceptively difficult as hell.

There's a ton of other factors, of course: Anime tends to work off of comic adaptations, which makes structuring their stories and pacing a whole lot easier, they work on a somewhat different seasonal schedule from American television, and the viewing habits/general attitude of their audience is different from having done things differently for so long that things which fly for Anime just wouldn't work, monetarily speaking, for a western production.

Add on to all of that the radical upheaval to the way TV is being produced nowadays with the monumental rise of streaming platforms, and it's no wonder studio execs have been at an absolute loss as to how to handle their new shows. Honestly, I think it has nothing to do with being story-driven, and way, way more to do with being broadcast television.
The Dragon Prince, She-Ra and the Princesses of Power, Kipo and the Age of Wonderbeasts, Centaurworld (yes, seriously), Invincible, Cuphead, and Arcane have all been story-driven cartoons that have incorporated varying amounts of serialized/episodic storytelling based on what they need and what they're going for, and have all reached satisfying climaxes to some degree or another depending on how far they've progressed into their given story..

There's an entire discussion to be had over the value and benefits/drawbacks of binge-watching TV shows, way too much to get into here, but even for the shows that were produced week-to-week like Invincible and Arcane, the fact that all the episodes are readily available for replay, all collected in one place, and CAN be binged all at once if the viewer wants to, means that the creators aren't as beholden to 'catching up' the viewers in each episode.
If something's airing on TV at a fixed time once per week and that's the only chance you have to watch it, you're going to lose some viewers who missed a week and feel lost, or you're going to gain viewers who were flipping through channels and thought it looked interesting enough to give it a shot.
That means you have to do this balancing act between progressing a plot to keep people coming back vs. having a satisfying story all aired/shown at once. As discussed above, that's not an easy thing to do, and just because Avatar could pull it off doesn't mean every show can (or even should; each story has its own needs based on what it's trying to accomplish.) Avatar was ridiculously successful, though, and has become a cultural touchstone for an entire generation of creators (hell, 2 generations at this point), so everyone wants to emulate its success, especially in the midst of their entire industry turning on its head and metamorphosing into something completely new and alien.

Independent series that aren't beholden to the weekly broadcast schedule are absolutely thriving right now, and while there's still some value to be found in shows on proper broadcast networks, it's rapidly becoming less and less worth the damage that industry causes to creative freedom.

Another advantage of this is you don't really have to worry about rushing to a conclusion to wrap up the season nicely in case you don't get a new season. You can commit to a pace that serves the overall story and who cares if that results in the season ending abruptly at an unsatisfying point? The rest of the story exists somewhere and the audience can go look at that if they want to know how the current arc wraps up. You're not doomed to have an unresolved story as the 'canon', the way you are if the cartoon is the only form in which the story exists in an official capacity.

IIRC in fact in anime this isn't a bug, it's a feature. I remember reading something about anime serving as advertisements to the manga/light novel they're based off of, in which case ending the anime unresolved is better for business than giving it a proper ending

THIS!!! I didn't like LOK because it seemed....weird? Maybe it's just me but i really hated how they made Korra to be strong ( as in muscles ) and "non-feminine" but made her to seem like "not like other girls"... I remember episode when her and Asami just meet and Asami was like "do you want to spend some time with me?"
And instead of saying yes/no, Korra was more like "Where? In spa??"
However, i did like that Asami is "girly" (not really but compared to Korra she is), rich but still smart, can do things on her own and is actually nice person ( So i don't think the problem is writers being unable to write female characters)

I do like that she is different than Anng was (personality ), but i didn't like how they made him such a bad father

edit; I LOVE that she is strong, i dislike how they made something similar to movies from early 2000's where girl can be either "pretty" or likeable

I think the popularity of binge watch shows has sort of popularized this style of cartoons.

I don't think necessarily that old shows didn't have overarching plots that spanned a season pre-streaming. Redwall comes to mind. Some shows did deal with continuity where events that happened in earlier episodes would be brought up. Like in Jackie Chan Adventures where collecting the Tailsmans would effect events later on. I feel like the difference back then was that there was more effort to have the episodes stand alone for those who might only see them Saturday morning or after school.

Something I am sort of sick of with modern day cartoons is this style of writing which Cartoon Network popularized starting with Adventure Time but was also used a lot in Steven Universe where nothing really happens in an episode but in the last minute there might be a hint at a plot. I watched some random episode of Craig of the Creek and it was the same thing, the whole thing was just fluff. I think this does tie into what you are talking about, that the episodes are just fluff that are building up to something bigger but it doesn't pay off.

I watched some of Pepper Ann recently, it's an old kid's show from the 90s. And watching made me realize that we don't really see a lot of these ground sitcom cartoons anymore. An episode would be 22 to 30 minutes with a solid plot, and I sort of miss that. I had some issues with the Proud Family reboot but I was happy to see a return to that format of show. It's sort of a balance between plot and character driven stories which I want to see more of.

Yet Anime has no ending because they always just do the first arc of the manga/LN.

And you know most shows die off when there's no more milk to be had.

I remember the last season of samurai jack being trashed for a too basic of an ending and something something women as always.

Star vs forces of evil had a mediocre open ending, I think in with the hope that would get more seasons.

The gravity falls one I think it was toned down to not get a sudden M rating.

Miraculos Ladybug is a show meant to sell stuff and for the most part you couldn't call it story driven. It gained a story. And I love how trash the MC is, especially because she looks and acts like an ex of mine.
Wish for less Cat noir bashing. But then again all cartoons and shows have an impossible time writing quirky, cheesy fun loving, but highly competent men. Doctor Who did it for a while, from time to time.

Korra, uh,, hm. I didn't like the characters?Or their choices? I enjoyed the setting but that's about it.

Steven universe, never watched never will.

Me thinks you are not in the target audience anymore but still want the same vibe with a story geared towards you.

I don't think you'll find a lot of those since they can't be marketed to sell trash or be on a platform rated for Everyone.

And the last problem is when people throw money at you. Imagine you're a writer you already did the ending. it was great it wrapped up in season 3 and everyone was happy. Then because you're still super popular someone throws money at you for two more seasons. Or a deal for another show of yours. What'chu gonna do?

I've said this before to friends, but here's what I think in regards to western-cartoon storytelling:

Something I've noticed in these cartoons is that they run on a storytelling style I'd dub "pseudo-serialization." Basically it's a series that has continuity, but said continuity is only ever majorly relevent for like the first episode, last few episodes of the season, and maybe a mini arc in the mid-season. Any other episode is just episodic status-quo hijinks or "filler."
It's a way to satisfy network standards so casual viewers won't feel too much like they're missing something, but at the same time satisfy viewers of the modern age who expect some form of continuity due to the advent of streaming services
They might set stuff up, but by the time it becomes relevent, they'll shove it in for only an episode or two before going back to status-quo hijinks; or they'll realize that they spent too much time dawdling around and they'll try to shove in loose ends at the last minute.

It's not a style of storyteling I appreciate and personally it makes it difficult for me to invest myself in Western cartoons because of this.