That's why I find the whole idea ill-suited for a movie. I've approached the concept from a lot of different angles, and that's what it boils down to; constructing a movie around dudes in rubber suits dry-humping each other to death.
The original comic did it decently, but it's been cherry-picked by the movies so much it would seem tired now; The fights didn't really ever take center stage, seen more from a distance from the human characters' points of views. It allowed you to have your fights without derailing the movie. It never cut from the characters to just the creatures fighting.
Approached like that, I think a decent story could be made. I doubt anyone would try it, though.