When I read your OP I thought you meant an increase over a short period of time. Yes, it has increased over time significantly. I think I discussed something similar on this board, so I may repeat myself, but I seldom had subs show interest in strap-on in the early 2000s. Now almost every application lists it as an interest.

Maybe one reason you are seeing more of it in Domme media is that it is less taboo. When NYC was in the news for actively trying to arrest people for it, it stayed underground.

The most significant uptick I have seen within the past few years is gender play (which includes strapon, feminization, forced bi, etc). I have been really curious about the origins of this. Are men becoming less homophobic? Gender play (at least in my experience) is less about humiliation now too. More men are more interested in feeling like a woman (pretty, desired, pursued), than being degraded for being less manly. I see that as a good sign.