I don't find it strange at all, pretty common, in fact. Where is a person, male or female on a 'clothing optional, suppose to put their stuff that they wore? They certainly didn't leave the house, condo, apartment, or hotel room butt naked. Wife and I have been going to a beach for upwards of 25 plus years, and on the blanket, towel, or what ever is where those shorts, tanks, and swim suits go. If there is a 'more better' place for it, I'm willing to learn.
Now I would like to know where the beer cooler is in any of those pix.