I get how a two parter could've worked, but I feel the end result would be two less epic movies rather than one huge epic movie. Sure, fans would edit them together as one movie, but the experience of first getting whole story in one uninterrupted sitting would be lost. It takes the magic away a little bit.
I also don't agree with how a two parter would automatically fix people's problems. Not necessarily the case at all. It could've easily introduced a whole new set of problems. The months between release would've been spent theorizing how everything would get paid off in pt. 2 (the way we all theorized in the four years between TDK and TDKR) and the end result could very well end up disappointing and/or too predictable to justify months of waiting. Bruce comes back, defeats Bane, passes the mantle, cements the legend. There's no
real cliffhanger in there. Yes, the story has a mirroring/halves thing going on there, but the film works better if you just enjoy it as the final journey of Bruce Wayne. Sticking a cliffhanger in there after Bane breaks Bruce or the siege of Gotham doesn't really work. It's not like it was some heavily guarded prison where we're wondering how Bruce is going to escape the prison. It's a big hole in the ground and there's one way out. We know he has to make the climb, and will make it. It's more about the emotional journey to get there- cliffhangers work better if there's plot to support it.
Having two parts wouldn't have automatically resulted in everyone having a more positive opinion of it. Rather than complaining about one film, the fans would be arguing which part was better, with some saying pt. 2 was too predictable and didn't live up to p1. 1, and others pt. 2 was great but pt. 1 wasn't satisfying enough, it should've been one movie...etc. etc. etc.
Bottom line is...hindsight is 20/20 and fanboys and girls
always find stuff to complain about.