Keys couldn't even scratch GG1, let alone GG2 (and if the HOX has GG2 is still up for debate). GG2 was
not an upgrade in scratch resistance, it was an upgrade in strength, more specifically, crack/shatter resistant. Which just means they can be made thinner.
Anyways, I would like to see tests with sand/dirt, which is more than plausible to be found inside of people's pockets, as well as having dirt and dust being trapped between the phone and something like a credit card and rubbing/sliding against each other. Maybe slide the phone face down on a sidewalk as if it had fallen out someone's pocket and slid. Those are more realistic situations than steak knives or box cutters coming in contact with the screen. And keys are just redundant now, which is why nobody is afraid to try it because it has been shown to be virtually harmless since PC World did the "Pocket Simulation" with the iPhone 3G.
iPhone 3G Torture Tests - YouTube
That's just my opinion though.