Well, despite some, so far unsubstantiated denials, that he's less of a diva than you would expect your average 30 plus million $ a movie scientologist dummy to be, I really doubt he'd leave really any of the flexibility in an actor that you would need in a comic-based potential franchise such as this one. It's opening in an ultra-challenging summer and if it isn't a runaway hit I don't really want to be left with a dead franchise after one movie because of his possibly damaged rep.
I don't think he's a jerk. I just honestly think he's fragile, eccentric, and as I said, dumb. An idiot savant for sure, good actor, master at making box office money, but I don't think sattling yourself the pressure of the NUMBER 1 A++ lister and really taking a wayy bigger gamble than you have to, when he's already 8 inches too short, 10 years too old, and more overpriced than you need. The kind of movie that needs a Tom Cruise to be successful is not Iron Man. It's formula roles. It's sheeple movies. Iron Man needs a different famous name actor that's best at exciting a different demographic entirely in my opinion.