The Lumia 1020 has a "Gorilla Glass 3" Screen, why should someone use a Screen Protector?
Before she had a 920, my girlfriend had a Lumia 800. The screen on the 800 managed to look as new until the day she sold it without the need for a screen protector.
We thought this was due to Gorilla Glass and we thought the 920 would stand up to scratches too.... But her new 920 picked up really, REALLY bad scratches after only a week. Not sure how it happen, we think it was from being in her handbag with keys.
At the time replacing the screen would cost half as much as the phone. I looked into was to solve and tried a few polishes but in the end it was easier to buy another 920 and sell the scratched one.
As you can imagine it took a few weeks to sell and we lost a fair bit of money on it.
From now on I will always spent the $12 on a good screen protector. The alternative is far too much hassle and heartache.