Re: Naked in public
I think it is such politically correct movements that one sees on college campus's for example, that have encourages a new prudery.
I think it's a combination of these things (not in a particular order):
1)
Increasing insecurity over one's body. Abercrombie and other image sources have raised the standards for what an attractive male body looks like. Compare the demands of the recent fitness level with the way men typically looked in the 70s, even athletes like John McEnroe. Big beautiful pecs and arms aren't enough anymore. Now, you have to have big muscles along with no body fat and exaggerated abs. Research has shown a rise in male body insecurity because of the increased focus on the sexual appeal of the highly-fit male body.
2)
Insecurity over being secretly photographed or video recorded. A lot of this likely relates to penis size insecurity. Otherwise, most of the jocks who are targeted for this should be proud of their bodies. Some older videos I've seen of changing rooms with pro athletes show the guys frequently pulling on their penises to make them larger when they think other guys aren't looking. So, even in an era where nudity around other men wasn't considered odd, men still showed signs of insecurity over their dick size.
3)
Paranoia, insecurity, and zealotry over gays and trans. A lot of the most recent prudery in schools, like having only individual partitions with curtains, is being justified as being a way to integrate trans students into locker rooms. It's admirable to integrate trans students instead of ostracizing them but I think they are being used as a cover for simply increasing prudery. After all, the very strong trend toward individual partitions and curtains, though, started with basic homophobia, long before trans rights came to the fore. Even the US military has been replacing group showers with curtained stalls, so homophobes don't have to worry about being looked at and judged (again, penis size insecurity). Restrooms all over the US have put in big urinal partition walls. It's very rare to find urinals that don't have them now.
Visibility of gay fantasy and identity — There has always been rampant paranoia and simple bigotry about gay folk but our visibility, as a result of the AIDS crisis and political protest, has been coupled with the rise of the Internet. The Internet makes it even easier for heteros to see gay fantasy and desire, making it all the more easy for them to justify a higher degree of prudery. It's good for us to be demystified, for who were are to be more commonplace. That reduces bigotry and paranoia. But, it also gives rise to enabling prudes to have things to more easily point to, like all the spycam videos of locker rooms and shower rooms.
4)
The trend away from physical activity toward things like video games. Kids who grow up glued to personal electronic devices are going to be less interested in physical activity in general and see less of a need to have it involve nudity. Their insecurity level is also likely to be higher because they didn't spend time, while young, naked around others. So, for them, being in that situation would be "creepy" and "weird". The trend away from the human body toward the mechanical is one that is only going to increase. Along with that trend will be an increase in prudery.
5)
Economic insecurity resulting in the loss of belief in the "American Dream" (including American superiority), translated into increased insecurity and a greater desire for control. Even all of our vehicles now look angry, as if people are now so weak that they need their cars to protect them. Maybe they are. Being naked around other people is a social leveler — it takes away the influence of clothes to define social class and worth. It also takes away an artificial barrier between people. In an age of increasing insecurity and thus an increasingly desperate desire for control, Puritanical interests are more likely to flourish. Most people want a solid ideology to cling to. The erosion of the "American Dream" has given rise to things like the Alt-Right's Dadaism, more moralistic witch hunts, and an easier path for Russian anti-Western propaganda to infiltrate our politics and consciousness. Not coincidentally, anti-gay witch hunting has become more prominent than ever in Russia, just as Brass Eye was forced off the air for mocking a particular brand of hysteria.