Yeah. I'll be the first to admit that Batman and Batman Returns are horribly flawed movies. The main reason they're so beloved to this day is the nostalgia and the overwhelming hype that accompanied them.
Bruce Wayne/Batman is almost nothing like the comic book character.
He's also almost nothing like "Darth Vader." Which makes sense, because the Bruce Wayne/Batman from the movie is
not Darth Vader, just as he's
not the comic book character. To expect otherwise, and to be disappointed by such, is irrational and not a particularly fair judgement.
It's a movie, not a slideshow presentation of comic book panels with voice actors reading the speech bubbles. You might not like the movie, but that doesn't mean the movie is flawed - just that your unrealistic expectations (that the movie be something that it's not trying to be) are flawed.
And he takes a back seat to the villains in both movies.
Why is this a flaw? This was a very deliberate decision. What makes it a bad decision?
I think Returns is much worse than Batman. The last time I tried to watch it, I actually turned it off. It's boring, childish, overly gross, has too many plotlines and characters, and "Batman" is barely even in it! It's funny how people complained about how "dark" it was at the time, but now it comes off as cheesy and campy as the Adam West show.
It's funny that you say this - many younger adults today have never seen the Burton films, while nevertheless being quite familiar with the Nolan Trilogy and subsequent Batman movies. I recently showed them to some younger friends of mine, who were skeptical and expecting them to be cheesy and campy. Their reaction, to Returns in particular, was surprising to me - they were blown away, saying it was far better than they ever expected it could possibly be. So I think the dark, serious aspects of the movie still hold up today, and the campy elements are possibly only overblown in those of us who have been familiar with the movie for the past 30 years.
For what it's worth, I think there are elements of the movie that are sillier to me today than they felt 30 years ago (mind-controlled penguins with rockets on their back particularly stand out) - and if I were making the movie today, I wouldn't have included them. But overall I don't think they're major aspects of the movie or its mood.