My hypothesis: There was a period from roughly the industrial revolution (you can pick which one) to roughly 2000 where we were rich enough that significant parts of the population lived in environments rich enough where nudity was not common and most everyone could afford privacy.

This led to the kind of weird you describe.

Prior to 1500:

- Homes would typically consist of one room.

- Clothing was expensive and somewhat limited.

- Bathrooms were the side of the path or anywhere else.

There simply weren't the economic resources for real privacy. Most of our accounts are from the upper class, who did have privacy (but who could -- and did -- also sexually exploit the lower classes as they saw fit).

I'd love to learn more about the typical life of people before, but there simply aren't resources. In a context like this one, you can read about e.g. rich Americans being concerned about unrest due to their inability to properly clothe their servants, but there are far fewer accounts from the servants (although, in American times, some). However, once you go before 1500, there is precious little from the illiterate classes constituting most of the population.