Just a couple of points.

You are just as likely (well more so) to be in a sauna with middle aged and old ladies as you are with drop dead babe types or whatever is supposed to be exciting.

We don't do public nudity to either flaunt ourselves or to be seen by others. It is something you do for yourself if you wish to. People congregate at nudist beaches to save the blushes of those who do not wish to see it.

In both cases it's just about prefering to sauna or to sunbathe without the restriction of clothes.

I like to do both these things but I do get self conscious if there isn't much personal space.