Superhero movies that kill off the villain

[Verisimilitude1984]

It's always bothered me.

Compared to the comics, for example Batman, the villain is always caught and returned to Arkham Asylum or Blackgate Prison. It's bothered me since Tim Burton and more recently Zack Snyder. I haven't watched many Marvel films, however the few I have seen, most follow a similar trend.

In the comics for a long time now, it's been established that the DC superheroes have a 'no kill' policy. It may bother some, but it was handled brilliantly by the graphic novel Kingdom Come for instance.

Aren't directors and film studios just limiting their potential for sequels? What do you think?

Also, in respect of The Dark Knight

[Show spoiler]I never liked the fact that Burton killed The Joker in '89, whereas Nolan didn't and I applauded that. Of course, he then went and killed off Two-Face so that was a bit annoying again.