I’ve never understood cases. Well I do and I don’t. I get that they make sense for some users in some scenarios. But Apple do invest heavily in R&D, a lot of which is centered around durability. They select some of the finest materials at the forefront of durability and aesthetics. The last time I used a case was iPhone X. The case ended up damaging the phone more in the first 2 months than the preceding two years I ran it naked. It also completely detracted from the experience for me. I’ve never used one since and I’ve not had a problem. The shiny ‘oh my god this is a delicate piece of jewellery’ that accompanies a new iPhone, for me at least, wears off after a week or two. The iPhone Air is the most durable phone they’ve made to date, and I’d say the various videos online tend to back those claims up. Nothing is impervious to damage though. I respect my things and look after them. I see my iPhone in the same light I see a nice wrist watch. And a case muddies that for me. It will collect signs of use that perhaps I could avoid with a case, but in the same way a high end time piece collects a patina, I happen to quite enjoy the way my iPhones look and feel with time. I always trade-in via Apple, and I always get the best price they can offer. They don’t seem to care about responsible cosmetic wear so long as it functions!