I don't think there is a consensus. Actually I've never heard anyone cite any specific harm at all. There is certainly an appeal to social norms and probably some ingrained racism: "we wear clothes unlike those primitive savages," but real benefit to shielding kids from nudity - what's the hypothesis to test against?
Which is very misguided! My ultimate parenting hack that I have discovered is to answer my kids honestly and in detail. This was born out of frustration when, as a toddler, one of my kids would become distraught when confronting the fact that she wasn't in our wedding pictures because she did not exist. Eventually I said "look, the egg that would become you was in your mother". A few how & whys later and she was fine before we even got into the mechanics of it.
Now I've honed this to the point where my kids just hear me go into that tone of voice and realize that they should drop the subject before the old man goes on another one of his 45 minute lectures. They've got more fun things to do.
