Who wants to see a movie about Krypton being destroyed? The amount of time spent on it in the first Superman film was more than enough. Not even close to enough people are going to want to go see a Superman movie where a bunch of intellectual aliens are waiting around for Krypton to be destroyed.
Smallville was far from perfect but they spent enough time on Clark growing up there.
Just give us a movie where Superman actually has to fight someone, not Superman Returns Redux. And make it someone other than Lex. The fact they have to keep redoing the origin story is proof of how no one can make a good Superman movie.
Batman Begins and Casino Royale were different since there hadn't been an origin story for either character. Batman has an incredible rogues gallery but he is really the most interesting and complicated character in the Batman stories. Only the Joker is as interesting as Batman.