It's 2022 and people STILL keep trying to make multiplayer porn games despite all the evidence that nobody really wants it. Maybe I'm the weird one and there IS a niche for this
I think the issue is in execution, things like SL end up making bank providing the tools to let people dive into their ERP fantasies.
There are people that sub to WoW exclusively to ERP in goldshire.
At this point, I think it's a matter of figuring out what makes people enjoy those sorts of environments and why other titles might have failed.
I personally think it's a matter of that initial social interaction before you get into something and having a world in game where ERP is just a part of the greater picture.