I just use a case. It's nice.

I have nothing against buying cases but let’s be honest, if the answer to a genuine solvable hardware problem is to buy more hardware then you have to sympathise with those who complain about the insanity of the current market.

Why commit to small differences in an entire inventory/supply chain problem for a very complex and expensive device instead of a thin wrapper?

Phones are thin! The case makes them reasonably sized. Treat a naked phone the same as you would a naked human: unsuitable and unprepared to go outside.

But if phones were built more durable would they be smaller than the thick case or could they make use of the extra space that a case requires by having larger batteries, etc.

This. I don't want to use 3mm of leather to stop my phone wobbling on its stupid camera-lens tumor. I'd much rather use 3mm of more battery.

I never get a phone case. I’ve dropped my iPhone XS I don’t know how many times. Not a single scratch or crack on it. Pro tip: needing a case is a marketing gimmick “it’s made of glass!”

Which negates the point of buying a small phone.

Yeah, I don't get why phones have to be as thin and fragile as possible. They look gorgeous, but are so flimsy you need to hide them in an ugly case that undoes all the work in making them thin and pretty.

In some ways, the best design is still my old Motorola Milestone. Rubberized steel, and indestructible. No case needed. Small, better looking than anything in a case, and it had a sliding keyboard to boot. I still miss that.

Smartphones these days look more likely jewellery than any sort of practical device.