If you want to read about comic books, I strongly suggest this:
https://www.amazon.com/Eisner-Miller.../dp/1569717559
and this
https://www.amazon.com/Marvel-Comics...7134822&sr=8-1
As for what you wrote... At this point it would probably be easier to say what ISN'T a problem with superhero books today. The publishers are basically relying on the loyalty of longtime readers. But - even without taking into account the bad gimmicks, the high prices, the repetitive storylines - the point is the format itself. Superhero books have become the niche, which means that all the neverending debates about Wally West vs Barry Allen, the no killing rule, Superman's trunks and whether they should kill Lois Lane are completely, 100% meaningless and irrelevant once you take one step outside the niche. The only people who care about this stuff are longtime fans lost in self-referential, nerdish discussions, and they are basically the only ones who buy the books on regular terms. Once those fans will be too old or uninterested to keep the ship afloat, DC and Marvel will become more or less like Valiant is today, or maybe even smaller.
The point - as always - is what you give to the readers, how loyal/honest the creators and the publishers are towards their mission. One example: Attack on Titan gives the readers an excellent and complex worldbuilding, relatable characters, a compelling storyline which goes towards a specific direction so you feel encouraged to keep reading because you will get closure sooner or later. Not a masterpiece IMHO, but very clear and successful in what it's trying to achieve. Another example: French illustrator Moebius was probably in the top 10 best artists ever. Artistically speaking, he was a monster; even if he died in 2012 he keeps having a huge influence on all kind of comic books and movies (a recent Ridley Scott commercial is clearly inspired by Moebius:
https://youtu.be/Y1ruuTs134k. Of course, it's a completely different kind of comic books from manga or superheroes and it is possible that if you have read Batman for your entire life you won't understand what the heck stuff such as L'Incal - Moebius' most widely known work - is about. But it is somehow irrelevant, because the dreamlike atmosphere of his comic books - often written together with Jodorowsky - is so strong that it's hard not to get lost in it. So you read Moebius' stories just to get a taste of their alienness and atmosphere.
Let me give you one last example - this time one which I feel very close. I will give you a list of some of the most successful creators/comic books in my country (Italy) - this stuff sells hundreds of thousands of copies every time a new book is out:
1- Writer/artist Zerocalcare: in its most successful books, he basically creates graphic journalism from war zones (Kobane etc.), very politically oriented.
https://www.fumettologica.it/wp-cont...erocalcare.jpg.
2- Writer/artist Fumettibrutti: the creator is trasgender and some of her works are basically underground comic books with strongly erotic content, focused on LGBTQ+ teens
https://thevision.com/wp-content/upl...ato-repost.png
3- Writer/artist Sio: surreal, silly-beyond-belief comic strips for kids, originally created for the web:
https://pbs.twimg.com/media/DmZg5wHXsAAD1mG.jpg
4- Classic character Tex: a western comic book which have been published non-stop for 80 years, monthly 100-page issues for 4 euros
https://shop.sergiobonelli.it/resize...?1559556763000
Besides that, there are, of course, tons of other books, including mangas (strong sellers among teenagers) and Marvel/DC. And European graphic novels, of course.
Please note that I don't want necessarily to imply that the titles above are examples of what comic books SHOULD be, because I have a few criticisms about all of them - and I also think that there are healthier markets out there, including France. But the point is - if a reader buys any of the bestsellers above, he/she knows what they are getting - at a VERY reasonable price. If you get Tex, you get old-style adventures, cowboys and horses - basically, you get entertainment. If you want to read about LGBTQ or getting involved in political stuff you get Fumettibrutti or Zerocalcare. And if you want silly, silly fun, you get Sio. And of course, you have other choices - including mangas.
So... For comparison, just think of all the other attempts superhero book publishers made to modernize the genre. Are they completely honest/loyal? Why should I care for Superman's death, if I know he will get back? Why should I care for ANY superhero series, if I will never get any closure (well, except for some miniseries I guess)? Why should I care for DC turning Alan Scott into a LGBTQ character, if it sounds incredibly fake? And aren't superhero attempts at saying something about politics somehow weak or not as convincing as a 100% political OGN about Kobane could be?