All this is so unusual and amazing. But there is something else that confuses me. I follow a dozen threads on my favorite games. And many other gaming thread that I visit from time to time. At some point, people always ask the developer what software tools and hardware they use.
And it's always the same answer. The vast majority choose DAZ as the main tool for creating the graphics part of the game (Blender as an additional tool that does not replace DAZ completely). Correct me if I'm wrong with this statement, but that's my observations. Hardware performance is always not enough, almost everyone writes that they are saving money for upgrades. Except maybe DPC, who wrote in his dev log that after he upgraded his hardware, he started wondering what to do with the extra GFX power. And judging by the fans' butts burning so brightly, they didn't exactly like what he came up with.
Only a couple of games out of the several hundred I've seen here use Unreal, and they're not AVNs, they're dynamic action games for adults.
Sure, most of the developers here would be considered amateurs by your high standards, but that's the situation in the AVN niche, most of them are made by talented individuals or teams of two, where one is a writer/programmer and the other is a 3d artist. All of those experienced guys you mentioned seem to be working for fat salaries at larger game studios.
So maybe there is a reason why they don't choose such powerful and advanced tools as you are promoting. They may not be able to afford to spend months developing each 3d model or an environment object, even if it produces great results as you have shown in the links you provided. Although for me they don’t look as impressive as Ocean’s pictures, but this is just a matter of preferences I guess. I’m an amateur 3d art observer, just like these AVN devs are amateur 3d artists, and I probably haven’t developed the right taste yet.
Therefore, they simply use free assets or buy them from those who do this professionally and customize them to suit their needs. Perhaps they are just sticking to their goals and their goal is not a perfect 3d model, but an AVN game which consists of graphics, plot, music, characters, storylines and more other things. And perhaps the ease of 3d modeling and rendering that their tools provide is the key factor that allows AVN developers to release updates to their games at least once a year, while working alone.
It's even more amazing is how these amateur devs, with the help of such an amateur tools, are able to create such artistic pictures that look much better than those made by skilled professionals.