If you have superheroes or characters that exist in the same world, and you're doing movies of them, wouldn't it be fun to put a couple of them together in one movie? Audiences love that. It's a natural thing to do that.
Stan LeeComic books are just a way to show a story. Then there are the movies, and television and exhibits like this that take the stories and make them seem so realistic. In the comic book, you're just reading a story - hopefully a good, exciting story that whets your appetite for all of this stuff to come.
Stan Lee