Posted this a few months back, and feel it has relevance to this topic:
"Who said Batman wants to be redeemed? In addition to preserving Dent's image as Gotham's hero, there's a reason Batman didn't simply have Gordon tell people that Dent just fell (despite the polce already knowing a situation was up). Even though Batman gets the job done, he realises that his methods are not pure, that he does cross a line that a "hero" shouldn't cross. It's why he tries to set Dent up to take his title. Not just so he could be with Rachel but because he believed the image of Harvey Dent, of someone who could get the job done within the boundaries of the law, was the type of "hero" Gotham should be worshiping. If Batman clears Dent's name but doesn't take the blame for his crimes, then the people of Gotham will automatically turn to him [Batman] as their hero, and Batman simply can't have that.
Obviously Batman is so much a part of Bruce & means so much that he cannot find it in himself to cast the persona aside (really, what is keeping Batman from taking off his mask when he's confronting Two-Face & bringing Harvey back?) and will continue to go out & do what he has to do, but not as Gotham's "true hero", because like Bruce said: "Gotham needs a hero with a face.""
This is where the great tragedy in Nolan's Batman films lie, IMO, and what makes them such a great films. Gordon fully believes Batman is the hero Gotham deserves because he is willing to sacrifice his public image and reputation in order for the city to carry on. But Batman doesn't fully believe that himself. A true hero in his mind wouldn't cross the lines he crosses, and would act more like Harvey in that he uses the law to bring criminals to justice. But at the same time, Batman is a persona Bruce just can't let go of, can't live without. The two are inseparable, so while he believes that Batman cannot be Gotham's true hero, he also realises that because he can't let go of Batman that Batman becomes easily redefinable to suit Gotham's needs.
Bruce has locked himself onto a course which he may not be able to escape. A course in which he is dedicated to serve Gotham, no matter what the circumstances, until the day he dies.
Spot on.