Swiping from the edge of the screen is not always easy with a protective case on your phone, as it impedes your ability to do so. Pretty annoying problem that I haven't seen that considered in many places.
I'd prefer a phone that is built from the ground up to be secure without a case. My current phone is a Nokia Lumia 920, which can withstand some pretty substantial forces [1] without breaking and without needing a case. And sure it's thick compared to a naked iPhone or SIII, but it's thinner than those phones with a case that would allow them to withstand the same kind of impact. Why do people put up with buying a phone and needing to immediately wrap it in protective rubber and plastic to keep it from shattering? Don't put up with it anymore! Demand reliable hardware! How well it works with a case shouldn't be a determining factor.
-Naked Nexus User.
A case that provides enough of a rim so that the impact doesn't hit the glass front directly is useful.