I know, but I never drop my iphone, and there is no guarantee that the gorilla glass can survive from a drop anyway. However, I hate any scratch on the screen, and I don't like screen protector either.
If I have to choose.
1) glass shatter from a drop, unless you have a very good case to protect it.
2) glass scratched, unless you have screen protector.
I will still choose number 1.
May be it's the reason why Apple don't go to this way, because they don't want to be blamed by the public that they make "easy to break" phone.
Anyway, I am still in doubt if the sapphire glass is that "weak", I never heard anyone can break the rolex's glass. May be the touch screen ability is limiting it's straightness. Or there is some other limiting factor. For example, weight concern (may need a thicker / heavier glass to make it drop resist + scratch proof).