Like others have said, VR is a niche, and the money/time commitment involved in producing it has made the bigger studios very risk-averse. Anyone that spends enough time on this forum has it constantly beaten into their heads that every new actress/director/concept has to perform in the metrics immediately or get abandoned. It makes for more generic content across the board.
I mean, look at every Original now - John Strong, young newcomer, generic set-up, armpit fetish, creampie, end. Over and over and over. That's what Alex Nash wants to make, it's what his fanbase wants, so that's what gets made. It's not exclusively an SLR problem. You could tell me that Badoink was making their scenes with an AI at this point and I'd be inclined to believe you.
People can point to stuff like the Ghostbusters or Mile High scenes not doing well, but that's ignoring the problems those scenes actually had. The Ghostbusters scene was presented as some Halloween cosplay thing but it was just a standard gangbang. There was no set-up, story, or characters, and a bunch of people complained about having dicks in their face the whole time. The Mile High scene was unwatchable for the first segment in the car because the camera was all screwed up. What then followed was a standard 3-on-1 with a bunch of girls that had done a million VR scenes before. People like innovative stuff when it's actually done well and is actually doing something novel.
Flat porn is going through a sort of renaissance now where weird shit is getting made all of the time. VR porn has seemingly gone backwards. The 4K era has a lot of outside-the-box stuff that has been mostly abandoned since. The quantity of VR porn is higher than ever. The variety, not so much. Even the smaller creators are mostly just trying to chase what the bigger studios are doing, or they're just a front for some rich old guys to fuck pornstars and they don't actually care about the content.