Sure , but houses rarely burn down. Computers crash a lot. In fact, I'd venture to say that most (or maybe close to most?) computers end up in some state where their owners either can't or think they can't retrieve data from them. Based on the likelihood of this happening to their customers, it'd be decent to let users re-download media you know they've already paid for and been given access to...
In addition to this is the commonly stated idea that you don't own a copy of a movie, you only have a license to watch it. If that's the case, I should be able to acquire the movie data assuming I have already paid for a license to watch said movie. Right now, consumers get the worst of both worlds.
