I don't feel any of the movies were tied down because of Avengers.. the only connections were some Shield scenes in the aftermath and maybe post credits scenes and those were self contained and had no relation to the main movie plot.
"Tied down" may not be the right term, but it has felt to me like the studio was trying a little too hard to make all these characters fit into the exact same world and style, when they may not have been what's best for each individual movie.
Maybe Incredible Hulk could have been a lot more gritty, or Thor a lot more poetic and fantastical. I just think it would have been nice to see one of these directors do something as fresh and different with their
movie that Nolan was able to do with the Batman movies.
Instead of just making something as safe and audience-friendly as they possibly could each time.