I really like that they are (at lease loosely) basing the movies on comic book stories.
These days comic book movies seem to go off the rails when Hollywood writers with no clue regarding what makes a character tick try to rewrite everything.
I think that is a bit unfair.
I don't think it is all that easy to take a comic book story and duplicate it into a movie. I think you can take the general framework of a story and turn it into a movie, but you are going to run into a bunch of barriers along the way. Things that don't transfer well to the big screen. Things that can be done better or make more sense to the viewer if done differently.
Remember, if you are an avid comic book reader, you probably have already perused the back story in previous issues/other titles. The average movie goer has to have that explained to him/her in a very short amount of time.
In addition, comics go back and rewrite the back story all the time, to make the new story fit into where they want to go. They create some cataclysmic event, or alternate dimension that allows them to start all over again. That is not as easy to do in the movies and would not be as easily accepted by the viewer.