With heavy grinding required, you can't know when you'll get the girl (and random is always bad, as I said before), plus it takes months to maximise her, while other girls keep piling up. This is the hamster wheel effect that kills any will to keep playing a game.
I don't mind the grind to get girls so much. There isn't a ton to do in this game. The grind to max them out is definitely hamster wheel material. I have 5 girls who can be 5* and I'm absolutely dreading trying to max them out. I suppose the logic might be that if it's too easy to max them out there isn't enough content.

They need to actually start making events with a storyline of some kind.