Hollywood is a land of money and cowardice. Every big film is basically a $150 million gamble, so they tend to play it safe and stick to a successful formula.
Nowhere is this more evident than in the genre of big-budget superhero franchises, where it's been decided that you must follow most if not all of the eight rules below:
8 (Pointless) Laws All Comic Book Movies Follow
http://www.cracked.com/article_16176_8- ... ollow.html