While i prefer the main routes art to stay with the same artist for consistency's sake, I see no issues with having another artist drawning art for the game.
Specially if this speed up those alternative scenes, backgrounds or extra stories.
i'd like to say i respect your opinion, but this case is different:
first of all, he draws as everything is covered in oil.
second, he draws pretty small dicks in a world where futa exists and should have huge cocks, and that's a focal point of this kink. Hell my dick is bigger and i consider myself as average.
third: he draws the same face for everyone but only changes the hair style.
fourth: the continuous change of style clashes a lot. I don't like knowing a character drawn by xxx52 and then finding myself with an anime ripoff of it.
Seriously think about it: In the beginning they mostly used xxx52 art because apart of being objectively better looking, it also allowed it to be animated relatively easy. The other artist's art, as far as I remember, has only still images.