Superman Returns isn't everyone's cup of tea. Hell, Spider-Man 2 and Batman Begins aren't everyone's cup of tea.
It's just with the Ultimates, you have the whole movie right there. I mean, it's just laid out perfectly, to rip that apart, to edit that in any large fashion, you would lose really one of the best things about the book, and personally I would just take a regular Avengers movie if that were the case. God knows most movie adaptations are already halfway to being the same as Ultimate versions already.
All IMHO, of course.