Empty houses no one moving in

I recommend looking into the MC Command Center mod for this. It adds this sort of story progression to the game, houses filling up, townies getting married and having children, etc. It's very very customizable. Down to number of children, if they should have affairs or not, etc. There are a lot of settings, but there are several tutorials on YouTube for example. Google it and you'll also find instructions on how to download. (It's free, naturally). It's updated every once in a while, especially after new game updates, but it's possible to keep the setting files between each update. I play generationally and I can't play without it, cause my neighborhood would die out if I did. I want playmates for my sims children!