On the subject of what was around before speedos, I just ran across this erotic "art" site: :D

www.human-anatomy-for-artist.com

Now if swimming in the nude would make a come back, we would all be in 7Th Heaven.

I doubt swimming naked in swim class would get much traction nowadays, but I would do it rather than lose credit for sure. Would probably be more interested in trying it during a swim practice. See what impact the increased drag would have versus racing in a speedo during meets.