The phone looks much nicer without a case. And in my 10+ ceaseless years, I’ve only damaged my phone once (and, in that case, I doubt that a thin silicone case would have saved me). And in that one case, I just needed to replace the front glass. Cost about $40 IIRC.

So why would I use a case?

Your mileage may vary, though, if you have kids, are a woman (fewer/shallower pockets), etc.