Sophia was in that beach scene.
There was Sophia when Dylan dated Emma, and there was Sophia when Dylan dated Marie.
Sophia was there when Ellie was at the club, and Sophia was there when Ellie kissed Julie.
People aren't saying, "Get out, Dylan", they're saying, "I miss Sophia."
Showing Pepper's story as well as Tony's story in the Iron Man movie will make the Iron Man movie richer.
But the problem here is that you're saying that "for Tony's sake, for the sake of the Iron Man movie" we need Pepper's solo movie without Tony.
People aren't interested in Pepper's solo movie.
(Of course, if Pepper appeared in a porn movie, people's reaction would be enthusiastic)