Between the 3 family members, there are like 36 h-scenes in the Cookie Jar. Take out the few that do not result in any kind of sexual contact with MC (applying lotion to Mom's legs, for example), and you've still got over 30 scenes involving those three ladies.
Sure, they where the first, so they've got a lot of content - that's normal. The others will slowly catch up and these numbers will even out over time, once we get the dating, the prom, etc. That's what was always supposed to happen.
I don't know why one would stick to what's in the game now, when there's clear roadmap for about 3 years now, which indicates what's going to happen. One can't just ignore that and say that the game is about the family etc. when that's just not the case. Or to put it differently, the current roadmap has about ~450 different "items/points" and the family characters claim 60 of these.
It's all well and good to say that the intended core of the game is the dating mechanic and the school relationships and such, but that is simply in no way whatsoever reflective of the game as it has existed for years.
Yes, patrons voted for them and that's why they got their content first. It's just natural that somebody has to be first, but just because that's the case doesn't mean that it suddenly changes what a game was and is supposed to be.
Sure, some people started to like the game because there was a lot of incest in it, but it's not like DC made the smallest promise that these characters would be more important than others. That's all I wanted to say about it.