because screen covers look like shit. IMO there is no point in putting that or a big bulky case on and ruining the sleek and sexy feel of an iphone. If youre a person who cant take care of your shit, go for it
Ive had a naked iphone since day one and going on 2 years now. Its survived many drunken nights, in my pocket skiing, etc etc. Sure it has some scratches on it but its so worth it not to put a cumbersome otterbox or a screen protector that ruins the vividness of the retina display (or any display for that matter. Im not actually even a big fan of the iphone)