Your dismissive characterization is not really accurate. Even in the cell-shaded anime waifu genre, there is a spectrum of gameplay quality and gamers do gravitate toward and reward the better games. The big reason MiHoYo games (Genshin Impact, Star Rail) have such a big presence and staying power is that even though they are waifu games at the core, the gameplay is surprisingly good (they're a night-and-day difference compared to slop like Blue Archive), and they're still fun even if you resolve to never pay any microtransactions.
it's accurate. I'm willing to bet those games wouldn't have 10% of it's players without the waifu and sex bait and the gambling mechanics. And there are gambling mechanics present even if you are f2p in those games, i bet. You just gamble your daily currencies or whatever. And it's always just one click away to actually spend money.
Not to say I'm a hater or something like that. I played a lot of those back in the day. But it's more honest to admit the art and the casino mechanic make the brain excited... the mechanics are 'okay'.
Edit: I just had a random thought. One of the strongest desire of a person is that of aesthetic desire. To feel that our life is 'picturesque' or aesthetic or beautiful. Overloading the game with aesthetic beauty is actually genius since it's an easy and strong form of aesthetic (beautiful girls. not just sexy but 'beautiful'. As in their whole face and outfit. Also other aesthetic quality like purity, innocence, cheerfulness, cuteness etc. Waifu stuffs.). And it's often so saturated with beauty that all ugly things in the players' real lifes fade away. It numbs our 'life aesthetic check' since it's flooded with so much 'beauty'. That's why people who play these games say 'i dont even think about the waifus anymore, so the mechanic must be good,' cause that numbed state is the intended state. Wheny our aesthetic center is kinda 'numbed'. And that's probably why it feels so good to play these games. When you play other games your sense of beauty is not similarly flooded and numbed, so you're all too aware that this action of playing games is not 'beautiful' in some real sense.