I agree with you the group movies while good the first 2-3 times quickly lose their appeal. I actually started watching the Avengers again a few days ago (for the first time since the cinema) and actually couldn't sit through the whole thing. Singular character movies are much better.
More ensemble superhero movies never hurt. Maybe WB will think of something or add something we haven't seen yet. It's better to have the movie out and chose not to watch it then to not have the option to watch the movie because no one ever made it.