If you go to the roots of it the Abrahamic religions (Christianity, Islam, Judaism) see the natural world as corrupt and a barrier to god. Nature was something to be “conquered”, human impulses are sinful and sexuality is especially impulsive and therefore sinful. It encourages all kinds of stuff like adultery, kids born out of wedlock (a big problem back then), and STDs (generally considered a divine punishment for sex). Clothing also denoted social rank and was even enforced by law.
Only in the official public sphere, off to the side it is very sexualized. Ads and tv shows are full of sexual references. You hit strange limits though like genitalia cannot be shown in movies (not X rated) but you can use a fake penis on men and a merkin on woman which is ok for some bizarre reason. The US forced its prudishness with genitalia on the Japanese after WW2 which is why they pixelate it. It likely has its roots in the US as a mainly evangelical Protestant settled nation vs the more Catholic and reformation Europe. Eastern cultures also have their own rules about nudity and sex but it isn’t seen as inherently sinful.