Reading through the dev's Itch page, I'm not entirely sure where he's coming from. He seems to be saying he has a story vision but has no artistic skills and his PC can't run 3D software like Blender, VAM or Daz and that's why he chose a "lousy" engine like HS which is why the graphics suck.
Then he goes on to appeal for Patreon memberships and says he'll run a poll to decide between "3D, Anime and Cartoon"? Does this mean this "game" is just to show his story concept and he's gonna change to an entirely different format once he has enough money to upgrade his PC or procure external artists?
This is the first time I've seen such a weird approach to game development...
Also his graphics suck because he just conveniently used outdated out of the box HS2 without bothering to purchase or even use generic free mods and filters. Lots of top notch AVNs are made with HS2, this has more to do with his inability / unwillingness to invest in coming up with something decent with HS2 rather than the engine itself.