Any person who sacrifices his life for an innocent is causing others to suffer, provided he has family: Parents who'll have to deal with losing a child, a spouse who will have to deal with losing a husband or wife, children who will grow up sans a mother/father.
But I still consider that sort of action heroic. Spider-Man's sacrificing his marriage, not his life, but I think the same principle holds. And MJ did have the final say. That potential future daughter will never be born, but I don't see undoing a potential child as particularly immoral.
As for Aunt May's comments, like I said, I don't see much difference between that and "Save yourself! I'm not worth it!" Your typical superhero is not the type to not treat a life as precious just because the person's really old.