Oh, of course, this completely misses the point. iPod cases have nothing to do with logic.
iPod shuffle "skins" exist for the same reason 900 billion iPod cases exist: personalization. Sliding your iPod into a case you've chosen largely for aesthetic value (you'll tell yourself you did a careful feature comparison like a good geek shopper, but you're fooling yourself; you bought that Coach leather case for your mini because it looked good); protecting your iPod is a secondary consideration at best, and always has been.
Cases will be marketed as providing all sorts of necessary protection, and perhaps most of them actually do provide some measure of the same, but that's not why people buy them, when you get right down to it. If protecting the iPod is the iPod Case raison d'etre, somebody needs to come up with a better explanation for the iGuy.
My Shuffle Doesn't Need Protecting