I've heard people cite representation of societal flaws as an excuse for not fully developing certain comic book characters that are supposed to be villains. Do comic book villains still only represent societal flaws? Is that why they don't get character development, because they have to change as society changes?

I'm thinking mainly of Batman's rogues gallery, namely the Joker, and I'm wondering how some characters, like Harley Quinn and Poison Ivy, made the switch to anti-heroes, whereas other villains, like the Joker and Two-Face have remained, and probably will remain, villains.

Personally, I think it would be nice to experiment with all of them as anti-heroes in main continuity, or if not, at least allow the villains to be theatrical and over-the-top, especially the Joker, so that they're more like someone playing a villain on TV than someone who is actually a villain.