This is another highlight of the generation gap.
When I was single, the idea of taking naked pics simply didn't occur to my generation, and the available technology was far to cumbersome and clunky.
Now, people take pictures with the ease and frequency of breathing in and out, so it's a short step to capturing intimate moments and sharing them.
I think this is an age thing - I doubt you'll find anyone over fifty who has done this, but of course there are always exceptions.