^There was a certain character logic to it, though. He'd grown up in a prison that tortured its prisoners with the illusion of hope (a clear path to escape if only they could make the climb/leap) in order to intensify their despair. And like most victims of abuse who become abusers, he imitated his abusers' patterns, playing the same kind of mind games -- giving both Bruce and Gotham a sliver of hope before destroying them both. True, if you think about it, it does fall afoul of the standard "Why don't you just shoot him?" problem, but at least there was a character-based reason for his folly, and that makes it somewhat more acceptable.
Plus in the end he was planing to just outright kill Batman after Talia left to get the bomb, Selina just happened to show up and kill him before he could do it.