I disagree. With modern materials, the thinness is the root of durability compromises. I've used my Xperia XZ1 compact for several years without a case. I've dropped it on concrete floors, sat on it, and used it in the mud. There're some chips in the paint, but the fiberglass body underneath is fine. Any scratches on the Gorilla Glass 5 are barely visible.

My old phones with cheap poly-carbonate backs(cracks easily) and thin GG3(cracks,scratches are apparent) were fragile in comparison. The material science has improved with modern phones, but manufacturers choose to make fragile phones.

You don't need thick overmoulding and port covers to make a phome durable without a case. The materials are strong enough on the high end phones. The problem is that when you make the glass thinner and exposed at the corners, it will crack with much less impact. The overall thinness means less flexural rigidity (rigidity is proportional to thickness cubed), you can snap a modern phone with your hands. Cheap new phones get it even worse. They use flimsier materials to cram a better SoC in, and still are rarely waterproof.