I really don't care what anyone does, but I work in a hospital with a lot of high to very high earning people, and I have never seen a single person without a case. As fragile as iPhones are, not to be rude but, I think it's a bit asinine to use one without a case. I guess if you're never active, go outside, run with it, hike, take it to the lake, work on you feet, run around at work, etc., then it's fine, but most people I know spend a fair amount of time outside and would just constantly have a broken phone.
A case is cheap insurance. I don't have an iPhone to admire, I have it to use and for me, it's more usable with a case. It doesn't lay flat when on it's back, if you lay it face down (like I almost always do), you'll scratch the screen. It's not designed to be durable.
Back to the fashion topic....haha, never mind. That's enough of this silly topic.