This is such a fascinating thread. Thanks to ColorsWolf for starting it.
I haven't had time to reply until but have been reading for a while. People being ashamed of their bodies is, I think, a very real problem. I spent some time about 20 years ago studying a course that was very focused on learning how to observe movement in other human beings. To make it easier for us to see the movement rather than be distracted by flapping clothes, those of us on the course spent much of our time in our underwear walking up and down or standing in front of each other.
During that course, I lost my self consciousness about my body. People seeing me naked does not bother in the way it did before doing the course. I also learned that nobody has a perfect body. Even the very beautiful people on the course had areas on their bodies that were not perfect. The only perfection that you see is photos in magazines and those shots tend to be carefully posed and then air brushed.
I'm not bothered at all by my own or other people's nudity but it's not something that I feel moved to campaign about. I like wearing clothes. I live in a cold part of the world so they help. They are useful for expressing something of who I am. It's more comfortable for others to be around me if I'm clothed (I may not care about nudity but lots of people do). I'm not constantly being arrested for breach of the peace so I am able to be with my loved ones in a way that is useful to them and am not causing them lots of worry.
Unlike this guy who I do applaud for his commitment to his cause while feeling sad that he has chosen to abandon his family and loved ones to make a point that most people will never get.
Regarding the idea that animals tend to engage in sexual activity out in the open. I think that it very much depends on the circumstances for the individual - just as with people. Plenty of people have sex in front of others - they choose the others and they choose the circumstances. I think it is the same with animals.
Sex makes us vulnerable so at the very least, there is a requirement to be in a safe place.
Depending on the species or individual within that species being watched by others may be off putting or threatening.
Regarding subtlety in communication. The difficulty is that things that seem clear to the person writing are not ever so clear to the person reading. Both reader and writer view the words on the page through the lens of their own world view and that means that they will see different meaning in the words.
This is much more so with written communication than with face to face communication. It's something worth bearing in mind.