The End of the Nudist Era
"Odd balls & Loose Skin"
I concur with your observations.. I googled, The aging of the "Nudist" generation, and found a couple of blog entries.
But aging is just part of the change. The cultural change that comes from the young finding their own preferences, partially by learning from observing their elders experience, and remembering..and add to that, the medias' contribution to the perception of nudity..being nude..etc..The internet and cell phones have definitely changed the way people communicate..
From my personal experiences, I've noticed less nice looking ladies laying out by the pool at my local fitness club than just five years ago.. In the past five years, Women only fitness clubs such as
"Curves" have opened up..and, this lack of ladies could also be due to the fact the the sales staff warns them when they first join, about lecherous old men like me..
.more than likely, some of the other patrons complained and the rules changed...At any rate..I remember four ladies who would wear thongs out there..There were a couple chicks that would wear micro-minis..
you should've seen some of those old WW II vets faces out there..Priceless..those were the days..
I am sure there are some psychologists' and sociologists' studying this topic at this moment, and more so when the weather gets better..I'm imagining laying out nude on the beach and have some guy come up to me holding his
palm pilot 
taking a survey..