Because Spider-Man comics from the sixties and seventies reflect what makes a succesfull movie in 2008.
If Captain America doesn't punch Hitler in the face in his movie, the movie is awful, because you know:
EDIT: And Ultimate Spider-Man is one of the most universally well reviewed comics in a long, long time! Christ!
DOUBLE EDIT: And the entire POINT of the Ultimates line is to go a different route! *head asplode*