I don't know about hog skin being 1/2" thick. It certainly isn't on the legs and face. I think a lot of folks consider the skin to be the skin and the layer of fat and connective tissue underneath it, which can be a 1/2" think or more, but only part of it is skin. Combined, it does all help protect the hog.

It does do a good job of protecting the hog from bites. The skin will still be damaged by the bite, but because the venom likely won't make it to the blood stream, the damage is quite limited.