Dying is just a really easy end to a redemption arc - everyone gets to feel sad, and noone has to deal with the real consequences of what happened.

I've been working on a story where the former-villain sacrifices his life to save everyone else, and his daughter recognizes it as him not being willing to face the music--which she is, for the not-so-legal things she does. It really is an easy way out--I don't mind it now and then, and I think for some stories it is necessary (Star Wars, for example, follows a mythic pattern, so Vader living and things being messy would clash with that), but it's way overused.