I will say, that in 2022 I don’t think it’s necessarily shyness. We are now generally much more aware of the harms of UV damage to skin than we were in the 60s and 70s, and so there is actually a trend away from tanning and towards covering up. Which is probably for the best since skin cancer is the most common cancer in the US.
Japan and Korea, and probably in the future China, are big players in cosmetics and fashion these days, and those countries never had a big nudist culture and generally dislike tanning and nudity even more so. And their products are gaining ever greater market share in the West.
Our cultures are mixing together in this globalized world, and other stuff like K-pop is already big business in Europe.
Obviously this doesn't apply to everyone, but I do think it's a non trivial number. Maybe it's a vicious cycle and more exposure of normal sizes would help normalize expectations/views.
As society has become significantly less prudish about showing skin, the countercultural impact of total nudity has gone from total reversal, to being just a bit further down the free spectrum, and that gives the whole act in general less of a reason. It's a big deal, but not nearly as revolutionary, and so I would imagine most people would shrug and say "why?"
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Also, it doesn't really help that nudity is these days associated with the crowd of its heyday, who are now well into being senior citizens, and that just makes the whole thing even less cool.