Originally Posted by DACrowe
The GCPD would have cared even if he didn't kill Dent. He would be wanted for the murder of Maroni, Maroni's associate and at least one crooked cop. Killing a cop is a pretty fast way to "personalize" it with any law enforcement in the world.
However, even if it was just Maroni, Gordon would still have to go after him. Vigilantism is against the law. Batman breaks that law regularly, but when written in a certain context (i.e. Gotham is dire and corrupt), one can create a scenario where some cops will give him longitude long as he stays within parameters.
You want Batman to be Frank Castle. Besides the lone vigilante with a gun was pretty boring even back during the first Death Wish film, it would make the idea of cops working with him indefensible. He is then taking the law totally into his own hands and acting as judge, jury and executioner. That makes him a direct challenge to the authority and order of the system. That means he is a threat to society.
That is one very simple reason that he is not written to act that way. Nolan just chose to challenge the principle in a dramatic way during the second film. And, intriguingly, seems to imply that Batman has given up that rule in the third film. But by that point he is no longer a nightly vigilante nor is he a secret resource for the cops.
I don't want him to be Frank Castle. I want him to act smart and I don't see much problem if he kills in certain situations. I don't want him declaring "no guns, no killing". He's a hero, not an anti-hero. It's implied, that he wouldn't butcher everyone. He doesn't save Ra's, and it was great. He pushes Harvey and it was reasonable, he shoots at the truck - it was reasonable too. But I don't see much problem of him killing those thugs in Returns. It was in style with the movie and the story. I don't think anyone would blame him for that.
I don't want him to dance with bare fists (and camera gimmicks) against a group of people with fire arms. Where's his awesome arsenal of smoke pellets, flash bombs, tazers and stuff like that? Begins was great in this regard (except for a couple of scenes), TDK - too, Rises - not so much (but the tunnel scene was one of the best in the trilogy).