There are sequels because the freakin books have been out for sometime and they are going by those books. Duh. This much money I believe is highly because of the 3D ticket prices which are more than the normal 2D screenings. The next Batman movie may not have a 3D release because Nolan does not believe that 3D is anything special (thankfully). But I think it can outdo TDK if the story is amazing.