Do you recall how Ultimate Gwen Stacy died?as for the different audience that is only because more people watch movies then read comics. if a tv show or movie was to follow the ultimate story line i don't think that would turn viewers off. As for using gwen Staceys death that would be allowed. Naruto got away with death on toonami.
Stupid or not, it's a reality you have to deal with if you're making serious sugestions. You might as well suggest a Spider-Man/Batman buddy movie otherwise.As for not being able to use characters like kitty and johnny like i said before that is just stupidity on rights and such not allowing marvel to use their own characters.