That's mostly because we care about aesthetics. My work phone is some Samsung flagship model from two years ago, I don't have a case for it (because I don't give a shit his it looks). Its with me on all factory visits in dirty production environments and what not, dropped it multiple times, stored in my pocket or just thrown in my bag. Screen is not cracked, sides and back are scratched and dinged up, but nothing is broken. They're plenty durable if you don't care about minor cosmetic things.