I am neither an exhibitionist nor someone ashamed of my own body.
My view... hiking naked on any trail is discourteous. You can never be sure that you won't encounter anyone. Disrobing, to me, means you couldn't care enough about others.
OTOH, if you are bushwhacking miles off trail, then OK about the discourteous part, although for me, I don't think I would want to bushwhack naked.