Do people really restrict themselves to one type of play?
I love playing families, and think they added a nice bit in Island Living for that (not as much as I would have liked, of course). But I love witches too. And I love building. And lots of other things. I just want lots of all-round stuff :)
As for family play being on the back burners, I would say it's no different to any other version of the game so I am not surprised at the small quantities we get for it. You get a little bit here and there, along with bits of occult, bits of fantasy, bits of building stuff etc, but the main concentration has always been young adults - especially female young adults. I don't see them ever changing that, even if they last through making sims 5, 6, 7 and on.
