I refuse to use a case on principle. The idea that you need a case to protect a phone from everyday use is so ass-backwards it hurts my brain. (and was not always the situation!)
It would be so much more space, weight, and cost efficient to simply engineer in the durability provided by a case through the use of proper materials and construction. But apparently marketing thinks nobody would buy a phone that looks and feels out of the box the way a phone with a case feels. So we end up with these thin, elegant, glass and polished aluminum devices... that most of the population has to immediately hide inside a bulky plastic/rubber case to have a chance of surviving 6 months.
Imagine if a carmaker sold a premium vehicle with a polished metal and glass exterior that you had to protect under a vinyl wrap to keep it from rusting and chipping under normal use... they'd be a laughing stock!
I was thinking it's more like a reminder that your car's warranty is about to expire, so hurry up and purchase that extended warranty!