I'm actually with you on this one. He's gradually making improvements to the core as he's adding new girls. That's actually why threesomes were broken on 1.5b~f (I made a post about it
here and it's a result of him improving the code.). Is it better to rewrite a whole new core from the ground up? Ideally, yes. Practically, not always. As long as he's doing what this patrons want (which, from what I can tell, is more girls) and the game is running enough for his patrons to enjoy, as far as I'm concerned, it's enough.