People do, but they shouldn't have to purchase a case to have their phone correctly. I have never purchased a case for a phone and have no intention to start, myself.
>>bigstr+(OP)
Ignore my other reply as it was meant for another comment. Regarding your comment:
I mean, I suppose you're right. However, that being said, a case is a good idea nonetheless, just as is a screen protector. A good case protects the phone against damage from dropping, just as a good screen protector does the same for the screen.