How many times are we going to have to see Peter Parker watch his Uncle Ben die, become Spider-Man, and face the Green Goblin?
Or Batman face the Joker for the "first" time?
Or Superman fight Zod?
Superhero movies are getting stale because Hollywood is afraid to deviate from the stories that we all know. It's certainly not because of a lack of stories to draw inspiration from - the characters that studios focus their $200 million blockbusters on have decades worth of material to use.
Would using more obscure plot lines lead to better superhero films? It worked for The Wolverine, which was heavily inspired by a storyline from 1982 and is considered by many to be the best superhero movie this year (and is a success at the box office).