I really should stop reading threads that I know will make me mad
I just go back and forth between different mediums. I watched anime as a kid, kinda was done with it, hopped back in in my late twenties because I found a title that interested me a lot and I was like "Yo, I should revisit anime!" For me it was S1 of One Punch Man, which really was so beautiful and hit a really personal chord with me in how it related to success and creativity and capitalism--just a really well done season (S2 sucks, unfortunately, because the anime industry is weird and gives shows to different studios)
So I think you just have to find the right anime for the right time in your life. I didn't like Deathnote when I first saw it. Then, I started watching it in 2020 with my Bro and was like "OK maybe Deathnote was exactly on the nose about a lot of things that are prescient right now" and now I like it.
I agree there's an overwhelming amount of trivial childish anime that is oversexualized, I think that has more to do with a small industry that uses the same creators over and over and is really hard to break into--some directors make childish things that are stereotyped and oversexualized and they just keep getting hired. Anime has a really big problem of only hiring people that they know, instead of taking a risk on new artists, and generally not paying people enough.
That and kids is the biggest market to sell animation to, so they get most of the attention. There are adult animes, there's just less of them. And as for anime that was really wild and progressive for it's time, those risk taking anime were made at a time it was cheaper to do that, especially in Japan. Now it costs so much money to produce animation in Japan, I don't think we'll see another cowboy Bebop anytime soon.
As for problematic stuff, the best way to combat that is if their advertisers and investors pulled from their problematic projects. That's how things have worked in other creative industries that were making problematic stuff, and why Western animation studios are so incredibly careful. It's not much of a big deal if people on the other side of the world are like "I'm done with anime" youknow, that's up to the big money back in the mainland. Not much we can do about it.
I see this problem as less "growing out of anime" than it is "growing up requires you to exercise more choice with your time." Since anime is just a medium and not a genre or specific structure, there really is a wide variety to choose from, not all of which are going to be presented to you straightforward and might require you to do some searching to find. If you base your idea of "anime" on what you just hear about from most people, you're going to get a limited selection of genres that likely appeal to whatever's trending at the time. When you're a kid and less familiar with archetypes and tropes, everything is new and exciting to you, but as you gain more knowledge you have to put more effort into finding new things (provided that's what you want and not just comfortable, predictable stories for escapism).
It's like saying you "grew out of films" because the only films you're being exposed to are whatever big blockbusters are being marketed (maybe less so nowadays considering the pandemic) and you feel like all films are just loud action movies. Or saying you "grew out of television" because you're only being exposed to safe family sitcoms or convoluted dramas.
Anyway, if we're doing recommendations, one recent anime I haven't seen mentioned yet would be Keep Your Hands Off Eizouken, which is about three high school girls who found a club for making their own anime. It completely avoids most of the problems of how mainstream anime handles young girls - none of the characters are sexualized or made overly cute and the main three girls are pretty rounded out as people and fairly unique in terms of not falling neatly into specific archetypes. The show as a whole also goes really deep into the process of creating anime and, considering the number of artists on this forum, I feel like a lot of people here would be able to connect strongly to the themes.
I actually really got into anime when I was at the end of college. Part of the fact was that in high school we had to stay up till forever to watch anime on Toonami and I usually had school and it was also hard to find sub/dubs online. Then when I got to college I didn't have time with sports and classes.
Now I actually have a bit of time here and there to watch series but it's very different than I would have watched in high school or college. I'm really picky now what I watch just because I don't have the time or energy to watch 10 different shows at once.
I like action shonen thanks to DBZ, but I don't really watch much anime beyond that but I know some.
Even so, I get your point, and I think it is due to the more anime we have today and the way it is produced for it to be competitive in the market.
More seasonal anime, made to last 12/13 episodes, while trying to be appealing to audiences following trends (super-heroes, isekais, "subverted" expectations at the start), and it ends with several animes that lack soul and just copy what other do but tweaking some elements that don't improve them at all.
And even in manga.
There have been improvements in the industry of course, (an anime of a popular shonen manga like MHA being paused from time to time to have less filler and adapt the manga better with good animation) but the problems are still there and growing (we are still accepting manga on weekly formats that take mangakas a whole week to make for a magazine that won't let them end until it's not profitable anymoret, just search for Oda's schedule and Kishimoto's thoughts on Naruto's length!).
There are more factors to it of course, and I think growing up and getting affected by the "adult life's realities" contributes to enjoy something less as well.
I'm still going strong at 26, but I think part of that is because of how slowly and casually I consume anime generally. Even at my peak speed in highschool and college, I still didn't binge through that many shows compared to some folks that I know, so I feel like I still semi-regularly stumble into gems or well-rated classics that I just had never gotten around to yet. For example, I thought that Assassination Classroom was fantastic, but just stumbled into it last summer, some 5 years after it had initially aired. Another example that I see mentioned in the OP, Haikyuu, is something that I just started this week. Thoroughly enjoying it, but I see it's been out for a number of years lol.
That said, I do obviously think it's okay to not be interested in a form of entertainment media anymore. There are tons of options out there and if you're not feeling anime anymore that's okay 
Part of why I get through it so slowly is because a lot of my time is also consume drawing, reading comics, playing games, etc. And that's all outside of work sooo, yeah i definitely feel the time crunch and need to be choosy with your time!
bc you let me, here's my list, it's big but I go into each for a bit
Attack on Titan - Transitioned from action shounen to seinen. Humanity's locked up walls from giants who eat 'em, but they learned how to fight back oooh. This one starts off basic, but it undergoes serious development in later seasons, it's a vastly different show in season 4 with it receiving all sorts of praise calling it a modern classic.
Mob Psycho 100 - Action shounen, with psychics. Main character learns to become in touch with his emotions and gets wrapped up in some drama. Character development focuses on the main duo and it's great. Waiting on season 3.
Houseki no Kuni - Genre-wise, it's all over the place lol uhh brief summary: moon people like shiny gem people, shiny gem people don't like them back, battles ensue sometimes. It's a CG anime, yes, but it's one of the best. Slow burn, no season 2, I hear the manga gets insane.
Aggretsuko - Slice-of-life animal workplace comedy? A red panda deals with her daily stress by screaming and growling into a mic. Gets a little too real at times.
After the Rain - Slice-of-life romcom with drama. A highschool girl falls for her manager who's a father close to his 40's, more wholesome and serious about its approach than you'd expect with that description. No season 2, I hear the manga ended to mixed reviews similar to the anime's ending lol
Disastrous Life of Saiki K. - Comedy. A psychic schoolboy wants a peaceful life, but he gets a lot of weird friends instead. Think of anime as a whole, this show will make fun of it. It's dragging out the manga ending adaptation from what I understand to keep going as a show, I don't mind one bit lmao the original stuff is on par with the source material
Cells at Work - Educational action shounen. Every cell and bacteria is personified and they all come together in a body, comedic and violent. Very fun. There's also the more dramatic adult spinoff about an unhealthy body, Cells at Work: Code Black. Still enjoyable, just not as fun, if that makes sense.
Dororo - Historical fantasy action, not quite shounen, not quite seinen either. Awful father sells out firstborn child in pieces to a bunch of demons, the boy grows up and is pissed at the dad and the demons. A kid follows him around too, but the guy doesn't seem to mind. The main duo kinda carry the show in terms of character development
Promised Neverland - Psychological shounen, the action's in their heads. Kids grow up in an orphanage that ain't what it seems, the first episode usually gets everyone hooked.
Kaguya-sama: Love is War - Highschool romcom. Death Note, but two teens with crushes on each other play the most convoluted game of trying to get the other to confess their feelings. Season 3 announced, and I'm happy about it~
Carol and Tuesday - Futuristic music drama, by Cowboy Bebop's creator. Two girls try to make it big in a music industry that heavily favors the artificial in more ways than one. Starts off focused on the main two but expands quite a bit on the cast as well.
Stop This Sound - Highschool music drama. A group of highschoolers join a club to the koto, it gets competitive and dramatic real fast but it's pretty good at it. The main cast is mostly solid in terms of interaction, I imagine it'll be more expanded in the upcoming season 2.
Vinland Saga - Historical action seinen. Takes place at the end of the Viking era, that's all I'll say. Very character driven. Deserves a season 2, but the ending we got isn't that bad a place to leave off on.
Eizouken - Junior highschool slice-of-life. Three kids form an animation club, and explore the process of making an anime from scratch and on a budget. Light-hearted and light on character, but it's a fun one to watch~
Smile Down the Runway - Workplace drama, but stylish. We follow an aspiring fashion desginer and a short model on their journeys, who would've known the fashion industry was filled with divas and drama queens??
Somali and the Forest Spirit - Fantasy drama. A golem and a human girl become father and child, but with a time limit. The main girl being cutesy is somewhat misleading for first impressions of the anime's nature.
Sing Yesterday for Me - Romantic drama. A few people have weird connections to each other after graduating from highschool, whether that's flirty or bittersweet. It's all about character, man.. The ending's a little iffy imo it doesn't need a season 2.
Kakushigoto - Workplace comedy mostly. A mangaka has troubles keeping his raunchy manga a secret from his kid. We also get brief glimpses into the future each episode where a mystery unfolds little by little. Wholesome and endearing, season 2 when????
Appare-Ranman - Historical action drama comedy. Two Japanese guys end up in the US and plan to compete in a race across the US to get back home with the prize money. This is the biggest underrated gem I've watched last year. I desperately want a season 2
Wave, Listen to Me - Workplace slice-of-life comedy? This talkative woman is somewhat forced to become a radio talk show host out of her own will. Honestly, it's bizarre sometimes but something about the cast just makes it work in being funny. Can't remember if it's getting a season 2 or not
Akudama Drive - Cyberpunk heist action shounen drama. A girl suddenly becomes a criminal because of 500 yen, and the plots just escalates so fast while still being coherent. Fun as hell.
Taisou Zamurai - Sports comedy drama??? A gymnast in his 30's almost retires to injury, but gets inspired to become better than he was in his prime. This cast is also weird, but they work well together. This anime balances light-hearted scenes with its drama pretty well
Sk8 the Infinity - Sports comedy. Just a couple of guys being dudes, and skateboarding. This one's just a fun one tbh lighthearted and the skating scenes are cool. One of my favorites this season
Wonder Egg Priority - Psychological drama. Girl tries to save her friend who commited suicide by buying eggs and being sent to a parallel dimension. Edgy as hell, but it's pretty solid. Another one of my favorites this season.
Was a fan back in my late teens and early twenties.
I'm 45 and don't much care for Anime anymore. I was recommended Attack on Titan...I thought it was trash.
Even some Ghibli films I dont care much about these days. I like characters to not be walking tropes or have 4 expressions.
Still read comics and watch films in my spare time though.
But Anime just makes me feel I'm losing braincells watching it.
80s Anime was the peak in my opinion.
That’s a lot 
actually i’ve already watched aot years ago i just really hate eren lmao, and i’ve watched and read mob psycho it’s pretty good. Carol and tuesday i actually have downloaded them but never remembered to watch them, will check it again though.
A lot of people mentioned sk8, eizouken, kakushigoto and wonder egg priority so they’ll be priorities to check out. Sk8 looks pretty sweet. And also the rest of them. Thank you for spending time to recommend that many, it must be tiring 
I actually watched a lot of anime for a long time back then, like myanimelist back then(still not up to date numbers) in the mid 300 series i’ve already watched so far and almost half of them are non mainstream so i’m not exposed to only mainstream 
Anyway multiple people recommended eizouken i’ll definitely check it out, thank you 
Yeah, I hit 30 last year and my anime and manga consumption definitely dropped off a cliff. Not only do I have less free time, but I've also found fewer series appealing to me. Like others have said, most anime have teens as their target audience so I often find it hard to relate to the protagonists. They either have to have strong supporting characters to get me invested or an interesting plot that ends.
Of the past few years, the only new series I watched with interest were Death Parade, How to Raise a Mummy (cause it's just heckin' cute), and Dorohedoro. And the only thing I've read with interest is Siuil a Run: Girl from the Other Side.
I was really into anime around my 12-15 years, and ever since then I only watch what really sticks to me... I'm 21 and it is only now that I started watching a new series, Jujutsu Kaisen and that is only because I was told time and time again that it's worth it and yeah it is. But I have no plan of watching anime all day long I couldn't do that even when I was really into it. I overall just don't have much time.
Death note i’ve watched it when it was first come out and i was pretty young then so i was easily awed by it, but now it’s just ok Yes, there’s much less/ non existent pressure in anime industry to catch up with the ‘right thing’ and it frustrated me somehow.
I think i just grew pickier when it comes to anime.....
Some animes don't entertain me as they used to.....however, there are cases where i apreciate them more as i get older....
Death parade is gooooood and thank you for mentioning siuil a run it loooks soooo gooood i want to read them right away
As a teen I heard so many people say they grew out of anime, and I just went "nah that can't be a thing"
I'm in my early twenties and I frankly can't stand it now. Everything feels the same with the same plot with the same hero with the same friendship with the same terribly written women. I have like, 3 or 4 anime I still truly enjoy. I have their boxsets, but I gave away/sold any other anime I had. It just didn't do it for me anymore.
I think the biggest issue is every anime protag is like, 12. It's fun when you're 12, but not when you're 24. At that point you're just concerned that that society placed their trust for survival in the hands of a kid.
Same here. Back then my friends always came to me for quality underrated series/non mainstream gems. Then for years now i don’t want to have anything to do with it anymore. Now i’m kinda intrigued and will check out the recommended titles to see if they can spark something in me again lmao.
Yeah, believe it or not, I was actually gonna recommend more but I dialed it back lol from all of these, Attack on Titan was the hardest to recommend.. You kinda have to sit through season 1 and 2 before it gets better. It's hard for me to recommend it bc I know there's people that hate on Eren, but he gets significant character development in season 3 so.. It's a toss up of whether or not a person's gonna like him by the time they catch up lol