The point of the movie was that Bruce managed to break that self-destructive mindset (something that's really necessitated by the comics needing to keep him around permanently), having succeeded in saving the city.
I mean, Batman the character in Dark Knight Returns
may be, as Hound of Ulster
says, a guy who just never quits, but this
Batman is someone who needs to quit because it's destroying him.
I get the objection about him being completely out of the picture over eight years and not involving himself with even relatively minor criminals, but in the world of the movie replacing his vigilante myth of Batman with the white knight hero myth of Harvey Dent seems to render him unimportant.