Re: Apple's design
"It's not a design."
Indeed. To get it registered as a design Apple had to pretend that there was something special about the exact curvature and that this was non-functional. The moment you suggest that rounded corners make the thing easier to hold or to put in a pocket it becomes functional - and so is excluded from the scope of registered designs/design patents.
Now that decoration has fallen out of favour for technical products, it is very hard indeed to create protected features.