As expected, those opposed to the idea have never even tried it and preclude themselves from gathering up that experience. I don't get that.
The site that the OP linked is probably the worst representative of nude yoga. There are more and more such classes starting around the United States which are better focused on what it's all about.
I started with one of the 3 original ones here in Fort Lauderdale right when it started about 10 years ago. It is great.
You don't have the constriction of clothing getting in the way of some very complicated poses. The only sequence when I really wish I had something restraining the family jewels involves ending up arched face down with all your weight across your hips. Let's just say that I have quite a bit to keep out of harm's way.
The guys who attend are great, though not your typical gym bunny/meat head types. When I can't make it to class for extended periods of time I definitely feel the loss of flexibility and camaraderie with the regular attendees.
Give it a try. Only then will you know.http://www.nakedyoga.net/