Originally Posted by Eros
Incorrect, you cant fix a city in one night, it took years for the cops and the outlandish "dent act" to do its job. Batman could of helped out, and as long as rapists,murders, and evil exists in gotham Batman will always be "needed". A upsurd fantasy act cant stop muggers,murders,rapes,stealing and etc. It was those "small crimes" that cost Bruce his parents.
It was made clear in Batman Begins that this version of Batman didn't intend be there forever to beat up every single criminal he could get his hands on, but had the more tangible ambition to "show Gotham that their city doesn't belong to the criminals and the corrupt" aka, get rid of the mob's stranglehold on the city. By the end of TDK, not only is Gotham well on its way to achieving that, but he's destroyed all meaning his symbol had in an effort to make a martyr out of Dent.
Anyway, even if you don't like the Dent Act as a plot device, that doesn't change the fact that it's the reason the writers provided for why he stopped being Batman. It doesn't have to do with Rachel's death. The point is that things like Rachel's death do weigh upon him, but he's stripped of his usual method of dealing with pain- being Batman, which gave him purpose. That is not the same as "I am sad, I quit."