It's the same reason why they're never gonna undo OMD with Spider-Man: It sucks, but there's too much that's happened since that wouldn't have happened without it and removing that stuff would screw everyone else over.
You could always have Spider-Man just become an adult and marry MJ all over again.
Originally Posted by Morty
It would have been awesome if the writers had put as much thought into it as you guys do.
The laws of physics are not crying in a corner, they are bawling in the forums.