All about build quality
If extras like screen protectors and rubber cases are essential purchases then how come my Lumia 920 was dropped, run over by a taxi, left out in torrential rain for 20 minutes before I realised it was missing, and still worked perfectly fine when I finally found it again?
I'll admit I've not been so abusive with my Lumia 1020, although in its case I did demonstrate the effectiveness of the Gorilla Glass to a friend by first taking a pair of kitchen scissors to the screen and scratching it repeatedly before handing the scissors and phone over to him and letting him have a good attempt to scratch the screen. We then took it a step further and started hitting the screen with the handle end of the scissors to see if it could take a pounding. No scratches or cracks or any other defects despite our efforts to inflict some damage.