Vanilla and usual plot with not very realistic characters. Like the point of VNs is either it is super romantic or it allows you to be someone you can never be in real life.
Pacing issues and dragging out stories to pad the pocketbook (for subscriber based games). So many games just want to either drag out the plot or rush it along to get to the sex. It's foreplay... not a quip.
My biggest gripe is hearing/seeing a game with a banging concept but an execution that I feel would have been better had it gone in a different direction.
Mine is almost related to yours, it has a lot of characters to fuck but it doesn't want to put another route with a harem ending, my only complaint but what can be done: v
This happens unfortunately too often. Lots of devs think they will make a long epic at the start but fall out of love or burn out halfway through. But well, at least the rushed ending is still better than the abandoned tag.
When enormous harems of women are just incomprehensibly in love with the Horse cocked MC, usually there's just not enough character development to justify it so it comes off as sloppy to me, not even a good fantasy to indulge in.
Scope creep due to either ambitiousness or whiny posters demanding their fetishes. Now-a-days just seeing the AI tag makes me want to not give the game a chance.