One of the biggest story elements in Spider-Man: Brand New Day was the introduction of Jean Grey. She also explained that Cretton wanted the villain to reflect Peter Parker's own circumstances instead of simply throwing another giant monster at him. She explained that Jean Grey wasn't chosen because she's an X-Men icon. Jean Grey wasn't included because the filmmakers wanted to check an X-Men box. She was there because she strengthened the emotional foundation of Peter Parker's story, and in my opinion, the movie is much better because of it.