Why is it that in the movies, the hero always finds an easy way to kill the bad guy?

In Batman, Joker falls. In Returns, Penguin gets overheated. In Forever, Two-Face falls.
In Spiderman, Goblin kills himself . In 2 Doc Ock kills himself. In 3 . . . obliterated by accident. Somebody tell me why I'm strangling myself with these films.