Well, depends on the person. I do get some envy myself from time to time. not "why are they popular" and more "why am I not good enough". But I also compare myself to others as a way to learn. It's a tightrope
In my time of the 33rd century, if someone not like someone else's work, they am free to do cover or remix of work and it perfectly-acceptable form of artistic expression. Original artist have ownership of original work, but fan have ownership of self's experience of that work. And fan interpretation am extension and elaboration of fan experience.
This have led to many many unofficial Star Wars.
I understand now that you’re referring to the microcosm of your personal environment specific to you and your immediate circle group
– and -
I’ve been seeing this in the macrocosm of the professional creative work field as a whole.
I see ‘Disliking’ and ‘Criticizing’ as two different areas of expression.
I dislike something, I move on. If anyone deems that as envy, they’re just crazy and should be ignored.
I criticize something when I am investing my time in it to wish for a better version of that concept/idea. In that respect I prefer to offer insight and possibilities on how the concept can be better expressed.
That does not make me envious of the concept’s general acceptance despite me wanting more out of it.
However, IF I were to just rant and rave about how bad something is to everyone who can hear me and offer no insight on how it can be made better, I would in that circumstance consider myself being envious of something I don’t really like getting the traction I don’t think it deserves.
I agree that criticising something more popular does not automatically make one jelly. But if you're venturing into "I'm better" territory, you're getting into sticky territory...
its also okay to be jealous or envious sometimes.
It's good to think critically about why things are popular.
I don't think I've ever actually heard the "you're just jealous" argument in real life without it being a joke, though. XD
Things are better because they subjectively are. Look at the writing, art style, character design, pacing, layout etc etc etc. Could be something as a better title or better cover. or just more aesthetically pleasing designs. Copy, emulate and adjust
A few years back I once did a very in-depth and heavy critique of an animation an ex-friend made that I helped develop. A majority of the work on that film was done with the help of others but he only placed his own name in the credits. If I hadn't had the justification of him being a selfish jerk and ripping his friends off, jealousy definitely would have played a bigger part for writing that critique. He got to finish a project and show it off and I was envious of that.
I feel like the type of responses you've been recieving in regards to your critiques of popular media come from either of two mind sets. 'White knights', who would deem you of not worthy to say anything critical about the thing they love. Or, from people who may harbor those feelings and are reflecting your actions based on what they think. They know if they said anything on the matter they would face the same outcome. So if jealousy is where it's coming from with them, it must be the same for you. Sometimes the human perception of others can be narrow like that.
What I wrote is purely speculative. Every person has a different reason. All you can really do is respond to the people you know and who would listen to you. The rest is just.. unfortunately the internet and you can't really control that.
Well, heh. To be 100% honest with all, I have two reactions.
There's the knee-jerk reaction, which was stronger when I was younger like all emotional reactions were, which is the reaction that is visceral, hateful, spiteful, "I could do better," "I've written more lyrical sentences," "I've looked in my bedroom mirror and seen a hotter face/figure..." and all of a sudden, I feel this deep well of hot molten something bubbling up in my gut. That person wouldn't be on my radar except that they have something I believe to be undeserved. And I believe I deserve it more. That's the horrible ugly truth within me, and I hate it.
Then there's a second reaction that usually follows the first, a sort of "talking myself down" reaction, where I remind myself I'm not ever in competition with anyone except my past self. And the jealousy (let's call a spade a spade) within me, if left to fester, is a poison. And I have things to offer, and a story to tell, and a life to lead, that jealousy and opinion seeking and status anxiety wil only ever warp and inhibit. Mostly I do well reining that ugliness in. But man, that demon chases me sometimes.
That's the whole truth.
Oh man, I do get creative jealousy from a few things. However it's typically not any webcomic artists or webnovel writers. Mostly because the webcomic artists I follow and read are just freaking amazing and the webnovels I read are usually very well written or help inspire my own ideas on the genre without making me angry or put-out by the follower count.
...However...
I admit to feeling a bit of ANGER with only one certain series. One that is already published and has trilogy and all that.
This ticks me off because it is poorly written and contains ALL of my pet peeves when it comes to characters and dialogue.
Yet it made millions. Billions even.
I know it's mostly my greed that makes me jealous. But man it really hurts to think of my own stories or a lot of other really good writers who dabble in the same genre but don't get movie deals sniffs
Mediocrity often wins big with effective marketing. When there's a large market hungry for such fare, catering big to it is always a win-win.
Disney's SW 3logy for instance. 
I'll admit such instances do bring out some of that 'creative jealousy' and the best way to deal with that is ignore the feeling or come up with something similar and hope to tap into that gluttonous market. 
My new book, 'Shifty Grades of Bray' will be hitting the shelves soon. Fingers and toes crossed for my first ever 'million' sales figure. 
...
...I need to read this. Especially since I HATE THAT ORIGINAL SERIES!
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Criticism is hard imo. Because everyone has their own taste. Say Twilight or 50 Shades of Grey, many people consider this as trash because they think these two are shallow and cheap stories. The problem is many people do enjoy and eat up this type of stories. They're popular because they're easy to consume. I think there will always be people who enjoy shallow stuff. Personally, I think it's fine because like what you like. Not everyone like deep and complex story and they just want to have something fun even if it's shallow in other people definition. It's the same for art. Some people like beautiful and detailed art others are fine with crude and rough art. Example: One Punch Man by One. His art style is certainly far from perfect but there are people including me who enjoy it. On the other hand I don't like WLOP's ghostblade. The art is amazing yes but I feel like the story is disjointed. It's all a matter of taste honestly. Trying to put a standard on art and story is a fool's errand. Everyone will like what they like.
"What me like" and "what am high-quality" am two different spectrum though. Can enjoy something low-quality, can hate something high-quality.
Who is qualified to define something as high quality or low quality though? There are stuff that I considered as high quality that others deemed as trash.
I don't think most people have an issue identifying the difference between the two. There just an abundance of easy to identify qualifiers used to categorize them.
The issue is usually someone not able to articulate why they might prefer something of lower qualities without getting defensive about those choices.
I can google it just fine but I prefer your own definition so there won't be a miscommunication.
Though, if you insist. I disagree. There are mediocre stuff with high production value and good stuff with low production value. E.g. Undertale. It's an amazing and in my opinion high quality even though (I think) the production value isn't that high.
Basically it things that cost money or skill, which also cost money. So more or better artist, more or better tool, more or better material. It not guarantee high-quality, but production am at least high-quality in certain aspects. For example, Hollywood blockbuster am usually high-quality in special effects and acting talent but writing quality am miss or Mrs.