Okay everybody, what the heck is up with this phenomenon?

[The Meat Rod Cometh]

So, the difficulty with this conversation is that it is rooted in our psychological boundaries and what we find as an acceptable limit. Older guys who experienced high school gym locker room culture post during the Cold War Era (1950-1989) are prone to think of lockerroom nudity as nothing special and the norm whereas the younger guys, you say, value their sense of uniqueness and privacy. Those two beliefs are at odds with each other considering the military culture historically conditioned young men to think as a cohesive group (like a sports team) rather than as distinct young men.

• I personally think when you are a younger boy/man, there some latent fear of being nude for fear of being exposed to predatory sexual behavior. There is also the general awkwardness of adolescent development. So, awkwardness about nudity among other men makes some sense for younger guys, but I would hope that one would grow out of it over time.
  
• As one matures, the fear of being nude around other men subsides because (1) of more self-confidence is one's body and (2) you can protect yourself even in the vulnerable state of being nude. Being nude and nude bonding exhibits a certain degree of trust around other guys. With both my gay and straight male friends, I take it as an honor when they state that they don't mind changing or being nude in front of me....It means that they don't fear criticism from me and that I will respect their privacy outside of the setting.

Agreed, and I'd add a third point. The younger you are, the more likely it is that those who'd see you nude are part of peer groups on which you depend to some extent on building social and professional relationships (i.e. finding a summer job) so the potential consequences (good, bad, or indifferent) are greater. That dependence tends to fade over time so a guy's reasons to be concerned also tend to fade.

Both very good points that make sense to me.

 

[Dave NoCal]

It all comes down to what we are sensitized and desensitized to. In college, I lived four years in dorms with gang showers. After college, I started working out and swimming at the YMCA. If I was going to be upset about nudity, I would have been in a state of perpetual upset or had to drastically limited activities I found enjoyable. What I have not been very comfortable with is nudity in mixed settings. This summer my husband and I went to Barcelona and went to the local clothing optional beach most afternoons. The first few moments of nudity felt momentous. Then I drank some sangria. By the end of the vacation, I actually felt more comfortable in a mixed setting.
To the OP, it seems clear to me that your level of modesty has been a really significant burden in your life. I don't think it's men from time immemorial that have a problem, it is you. And it is you who have paid a rather high price. Perhaps you should consider working on understanding the origins of your phobia and overcoming it. We will try to help if you ask for it.