https://www.pornhub.com/view_video.php?viewkey=ph5b2e4b7e0c538
Unfortunately, unlike Twinkies (yay, Hostess pun), this series did not last forever, with this here being the second of 4 releases. Since I lack skills in reading kanji, it's my personal mystery why DEEPS has ended making such videos, they had their finger on the pulse.
Couldn't agree more.
Now I'm far from being able to claim having done an industry-wide research but based on the output a change has happened. It can be said, as it is a (sad) fact, that it's not because the Japanese society has started to value women more, they still call rape an incident and victim blaming is a national sport. The taste of customers hasn't changed that much either, at least not in preferences, but quantity.
My guess is that based on digital download and platform streaming (the latter of which is massive with otakus) more common themed videos have been watched more. I don't like to openly speculate, but it could be a factor, that for us guys plain sex videos need not much explanation as to why people like them, so the socially inept ones (the NEETs and the hikikomori) can bond over it easier, comparing to sharing personal preference on what they like in fights.