Every civilized culture on earth has norms against public nudity. Objectively there appears to be something more biologically successful about cultures where nudity is reserved for private spaces than those who treat it otherwise
Well, not every "civilized culture" has a blanket ban on public nudity, but more of a "there is a time and place you know", like doing sauna naked and swimming naked in rivers/lakes (common in the Nordics at least) or being semi-nude (topless) at public beaches in Spain. Breastfeeding without having to shamefully cover up also seems to be more and more accepted, at least in the countries I frequent (mostly around Europe).
I'm sure there are more examples of "civilized cultures" where it's accepted sometimes to be nude or semi-nude.
Every civilized society has norms for everything, that's the tautological definition of what being civilized means. It's how civilized people define success. But this is not culture (as per Nietzsche) but just the opposite of it. To think the two are synonymous is exactly what he attributes to Christianity.
The Danish mixed nude beach goer is indeed technically less civilized but no less cultured, free, vital or unburdened by social anxieties about her body or conduct, she's strong-willed exactly to the extent that she's uncivilized.