Your analogies make no sense. This is a phone we're talking about. Something you're going to keep in your pocket and take with you everywhere, something which you're going to be stuck with for the next two years. I don't know about you, but I'd rather any damage happen to a case than the phone itself. Yeah, you can go without a case, but if you don't pay attention to what you do with that phone at all times it's not gonna be in great shape after two years. I've only dropped my original droid once, but it was on pavement, and if not for my case it wouldn't still be in the nearly pristine shape it is now.
If we're going to get into silly analogies, I wouldn't think you'd be a fan of plastic cars, given your fondness for metal and glass when it comes to phones.