Well it's why i've always liked TLH and DV as the definitive Harvey Dent/Two-Face story. Two-Face's motivation in TLH, in which Dent only becomes scarred 2/3 through the story, is to get revenge on those immediately responsible (Falcone, Maroni and the ADA who gave Maroni the acid), after which he freely turns himself into Jim Gordon. TDK was this tragic but simple motivation, save they made Harvey also blame Gordon....which led to bad results.
In DV, he goal broadens to using the "freaks" (himself, Joker, Poison Ivy, Scarecrow, etc.) to wipe out the rest of the mob. If Dent had lived his plan would have been something like that but bigger, destroy all of Gotham's violence and criminals with extreme violence. A corrupt version of Batman.
I never liked how Dent becomes what he hates....a run-of-the-mill gangster. Nolan would not go there in a film.