Probably because of the dev's fetish. He clearly like big tits, harem and some kind of consensual sex slaves relation. I like them too, but it feels like his obsession is crazy to some degree. Clearly he can write something nice, and sometime pretty good (e.g. Alnilam's plot). But once he write the sexual part, all is about serving the master, playing the tits and the girls want to be dominated by a strong man.
His writing sincerely reflects what he wants. The writing seems bad because we don't have that obsession.