Actually, I believe the whole "Why does Logan's hair grow back in the same style (usually!)?" question was touched on in the background of Spider-Man and the X-Men as a topic at the Jean Grey School. There was some theorizing (I think this was all in one line) that it was somehow something he unconsciously controls, which would explain in-story both why his hair is usually the same but has varied in some circumstances (if it works with flesh too, it would explain that weird 90s no-nose period).