As cool as "I'm the hero Gotham deserves, but not the one it needs right now" is, it never really made any sense to me. Why does Gotham deserve Batman as a hero? Because it's fundamentally good? Just because no one wanted to personally blow up the other ferry doesn't mean those people are good. I mean, they voted to blow the other ferry up! That makes them immoral cowards, not good people.
The people of Gotham elect a governmental infrastructure that is at its core corrupt and ineffective. They are willing to vote away the lives of "innocent" people to save their own. Many tried to kill a completely innocent person (Reese) for selfish reasons. Rachel Dawes says in the first movie that there are good people in Gotham. Really? Who? The only good people left are Gordon and Fox. Everyone else are either corrupt, incompetent, criminal or dead. The fact that being DA is practically a death sentence shows how sick the city is.
Maybe this makes Batman the ultimate tragic figure. He's possessed by trying to save an unsavable city. An equilibrium is reached where Batman constantly puts villains in Arkham, only for the corrupt city officials to allow them to escape or to set them free. Maybe The League of Shadows are right and the whole city should have been razed to the ground. Were Ra'as Al Guhl and the Joker right all along?