Well real histories have been founded on falsehoods. In the U.S. Columbus is celebrated for discovering America when in fact he didn't and didn't even get here.
And it continues to be perpetuated.
Batman's original motivation (when the character was created) was born of personal tragedy and he wanted to fight against that happening again to anyone else. And he believed he had to go beyond the norm of becoming just another cop. He wanted to take the fight directly to the criminal element unencumbered by the limitations society has placed on law enforcement agencies and individuals. In a more modern sense he meant to be the ultimate badass town Marshall: "You're in my town now so behave or else..." His motivation and pursuit is indeed a noble one yet ultimately futile in any real sense. No matter how badaas you are someone is always going to think they can better you.
Now the Batman was also but one facet of his campaign because Bruce Wayne was also meant to be the rich man with a social conscience. He was meant to follow his father's example (mind you originally how much was really known about the Wayne's other than they were murdered?).The idle playboy persona won't hold much water with those who know what Bruce really does to help others and so it's just another disguise for the media and society at large.
For a man (or woman) to invest so much of themselves in such an undertaking it does seem silly that he'd be so undermined by a broken heart. And yet that's exactly the idea they're trying to sell us in TDKR. Yeah, maybe it's more realistic, but it doesn't resonate with the Batman of the comics (or B-TAS) who experiences setbacks and emotional disappointments and yet manages not to lose sight of his larger goals and continues his efforts. Hell, it deosn't gel with the guy we saw in BB and TDK.
To me this is a disappointment in TDKR. It taints the character of Bruce Wayne and the Batman, contradicting the person we believe him to be...or should be.