Big agree. It would be cool if at some point in the future after the game is pretty much complete, there would be alternatives to the main plot where we somehow switch in one of the npc's and have them contribute in some vital way (like you said) to the main plot. i.e making Yvet our accomplice and having her take part in the night activities.
I also hope for a route where we give more focus to Vi. I'm starting to appreciate her role a lot more after reading some specific dialogue from her/regarding her.