It's also desirable to nudge owner occupied properties towards efficient uses. For instance, there's loads of large family houses being occupied by empty-neste

It's also desirable to nudge owner occupied properties towards efficient uses. For instance, there's loads of large family houses being occupied by empty-nesters, while those trying to raise a young family are squashed into undersized townhouses. Shifting the cost-base from "pay a huge mortgage and a tiny property tax" to "pay a moderate mortgage and an moderate property tax" means it's more likely to be worth the hassle of moving to a smaller house when you no longer need the space.