Originally Posted by BatLobsterRises
I think you just answered your own question. We've seen the League of Shadows and the types of people they attract. People who have suffered injustices and are basically mad at the world. Given Bane's circumstances, it's not hard to see why he fits the bill. The fact that it's Ra's who actually rescues Bane from the Pit pretty much makes Bane the ideal candidate for a LOS devotee.
Another thing is that sometimes there is intended ambiguity in films. Now, we can sit here and argue all day about Nolan's intentions I suppose, but I really don't believe he intended for there to be any ambiguity about why Bruce quit being Batman. He says why, point blank in the film. With Bane's character, Talia's reveal creates some ambiguity, and this just invites us to take a look at all his words and actions in the film and examine them more closely.
But to me it doesn't ring true for a main Nolan villain. We were even given a solid reason why Scarecrow (a minor villain by anyone's standard) does what he does, He looks to see the reversal of power/fear. Nolan managed to show us what motivates the Joker to do what he does without even showing us any backstory. Why so much ambiguity with Bane? Even in the last few minutes of Tate's life when she is revealed to be Talia, her reasoning is shown more effectively than Bane's throughout the whole movie. I've said before that it is because Bane is just a poorly written character and I stand by it. It doesn't make sense for Nolan to have clearly stated a motivation for every single villain in the trilogy and all of a sudden NOT do it for Bane.