Growing up I was exposed to very little nudity and thus one's body was a private thing no matter the gender of others. Other than a time that I can't mention due to the rules, my first exposure to same-sex nudity was in Basic Training. Not being used to such a situation, it was awkward and I did what needed to be done hygiene-wise as quickly as possible and trying to draw the least amount of attention.
While I gradually become less uncomfortable with the concept due to repeated exposures, I still never developed an indifference to it. Part of the issue I believe is the fact that due to low exposure to casual nudity I also viewed it mostly through the lens of sex especially considering that other than institutional situations like the military, the only other experiences with being naked in a group setting has been through swinging. This further cemented my association of nudity with sex and even then I still felt some discomfort being on full display in front of others, especially at some of clubs where many attendees where of the clothed "looky-loo" variety.
Because of these feelings I've never been much of an exhibitionist and the addition of a sometimes feeling of minor body dysmorphia, especially about weight, has likely contributed to it. In fact posting solo pictures here has been one of the biggest steps in recent times I've taken in an attempt to overcome it. So I think for some guys that might have a lot to do with it as sometimes we forgot or don't acknowledge that men can feel the same shyness about their bodies due to feelings of inadequacy made possible by media and societal standards. Also for me, I've always been introverted and tried to stand out as little as possible, so my bodily feelings are likely an extension of that.
There is also of course the fact some may not be comfortable being naked around other guys due to not knowing the intentions of those other men and if one was to apply the endless locker room and urinal stories on certain websites to real life, such concerns might only be heightened or add justification.
While I gradually become less uncomfortable with the concept due to repeated exposures, I still never developed an indifference to it. Part of the issue I believe is the fact that due to low exposure to casual nudity I also viewed it mostly through the lens of sex especially considering that other than institutional situations like the military, the only other experiences with being naked in a group setting has been through swinging. This further cemented my association of nudity with sex and even then I still felt some discomfort being on full display in front of others, especially at some of clubs where many attendees where of the clothed "looky-loo" variety.
Because of these feelings I've never been much of an exhibitionist and the addition of a sometimes feeling of minor body dysmorphia, especially about weight, has likely contributed to it. In fact posting solo pictures here has been one of the biggest steps in recent times I've taken in an attempt to overcome it. So I think for some guys that might have a lot to do with it as sometimes we forgot or don't acknowledge that men can feel the same shyness about their bodies due to feelings of inadequacy made possible by media and societal standards. Also for me, I've always been introverted and tried to stand out as little as possible, so my bodily feelings are likely an extension of that.
There is also of course the fact some may not be comfortable being naked around other guys due to not knowing the intentions of those other men and if one was to apply the endless locker room and urinal stories on certain websites to real life, such concerns might only be heightened or add justification.