Bringing back a character who was captured is different from bringing back a character who died. The Joker was captured and not killed, he could easily come back in any capacity in B3, or he could just stay in Arkham and not be apart of the story at all. How are you going to bring Two-Face back to life? Sure, you can use the Lazarus Pit, but that would involve bringing back Ra's and/or introducing Talia into the script just so you can do it. So if you want bring Two-Face back you're infact bringing back 2 characters and possibly introducing a 3rd just for this purpose. But why would Nolan dig up characters that died when the threads left hanging from TDK, in terms of the state of Gotham and Batman's role, leave tons of possibilities to go about without bringing back dead characters? I want to see Batman deal with his new role in Gotham and the escalation of freaks and vigilantes without resorting to bringing Two-Face back from the dead in order to clear Batman's name. It would feel out of place with what Nolan has done with the story so far, and would feel like a cheat to me rather than having the story unfold organically.