It did stem from the problem early on that Feigie and the like were really unsure of how the movie-going public would take these franchises seriously. So they got Whedon on board to write quippy dialogue. It wasn't really heavy at first. Tony was more of a devil-may care type deal, but they really could of used that to their advantage in that he is just putting on a front to hide the immense pain of hi parent's murders and that he acted like a prick to them before he died, so there's an in character reason for that quippy dialogue, he's just hiding it to mask his pain. And when it no longer works he self-medicates with booze.
But Marvel movies don't really get that much depth to them, so eventually when the public accepts these ridiculous premises, these out of context and out of character quips still remain. A lot of times they're used to basically take a breather from the action, but all they serve to do is deflate tension.
The exceptions are Winter Soldier and Civil war where they're used sparingly and few and far between because the situation is emotionally resonant. And frankly, those might be the best Marvel movies because they finally focus on the ethics of a bunch of untrained lunatics with Godlike powers blasting away and what the government response would be. And since Tony has a very personal stake, he's a lot less quippy about it and serious for the first time in a long time,
I think its going to take groundbreaking stuff for the whole 'shame' of it to be removed. Animation in Japan has a long and storied history, telling detailed, visually beautiful stories that surpass anything the West was doing. Like Akira vs. a Disney film. Not to knock on Disney, but Akira is a work of art. It is breathtaking. Even if you don't understand the story, the visuals, the music, the animation all flow together. There's a reason its a classic.
The Disney songs just hold nothing for me, and while they maybe classics, they simply don't compete with
Akira.
Or my all time favorite classic anime,
Ghost in the Shell, which was the first anime I was exposed to:
So, what you really have are two divergent ideas. You have Disney movies, which are all for children, but contain little hints for adults to enjoy, and then you have anime which is exclusively for adults and contain complex adult themes.
So Japan hasn't really had a problem with it, but America has struggled because historically the animation industry has been exclusively for children. So there is still this disconnect decades upon decades later, where the cultural divide is still extremely strong and it is almost impossible to find Western Anime without quips or witticisims that take you out of the show.
Castlevania suffered for this a lot, even if it did take the Japanese style.
So really, the West does not have a history of adult animation at all. It is very set in its ways and fully believes that they're for children. Same with comics and videogames. These are the attitudes where violence against videogames comes in, nudity, sexuality and everything we hear about, because historically we have little basis for it in our culture where Japan has no problem and has been doing it for decades.
There's also much bigger female integration of mangaka and artists than compared to the American comics industry, for touting how diverse it is. So you not only have this barrier where people are terrified to take something like this seriously, you don't really have precedent for it. The closest I can think of is the Batman Animated Series, which was still largely for kids, but didn't have that tongue in cheek aspect and tried to be complex and dark. But that wasn't enough to alter the paradigm.
Most recently everything has been moving backwards in the West, where 'adult cartoons' are typically poorly drawn comedy fests with awful jokes. There are very little attempts besides some on Netflix (That Zeus show, the black samurai one, DotA, Castlevania) that are trying to adopt the anime style and the seriousness of it and transfer it into the West, with varying degrees of success. Its still no competition for manga and anime.
Truthfully, I see it very difficult for the West to even attempt Japan's style and thought process, because the cultural divide is so big. I mean you have SJWs and Comic Pros attacking manga because they're basically getting completely outsold by single manga series. I would bet money sales of Berserk has stomped all of Marvel and DC combined right now, even though Demon Slayer and Jutisju Kaisen are super hot right now.
And that's honestly trouble for American comics and shows, because Berserk is NOTHING like American media. And Miura's art is simply breathtaking as you can see his evolution.
So I feel like animation in the West is on a decline. Slower than comics, but unless it attempts to get serious without getting embarassed, I don't really see it ever catching on.