I've tried to walk through sand pine before. It can hardly be done. The little branches are as entertangled as briar and, your right, even naturally they are thick as fleas on a dog.
I've seen it in central Florida where efforts are being made to bring it back. It requires fire to seed and that, and development, may be the reason it is having a hard time now. I don't hear of it being used commercially too much. It's supposed to make good pulp.