I think one of the biggest issues with these movies are fans..know what they can be. I recently went back and watched X-Men 1, and that movie isn't very good, however it is a milestone, and one of the movies, that really kicked off Marvel's success. I don't feel it aged well at all, with poor character development, bad casting, small scaled. Up until then, we had gotten "decent" movies, none that have got the amount of fans interested as we do now, as per "GotG, Ironman, Spider-man 2".
After those, the expectations for movies are much higher, and as they should be some of these directors/writers/producers are god awful, and chances are..got into the position from knowing a guy.
Now, that we've had great movies, mediocre, or average, doesn't cut it..nor should it, for the millions these make, we as consumers deserve great, and these are average, and thats what I feel hurt/brought these movies down to earth, as bad movies.