Making a house completely out of the styled rooms? It could lead to some interesting builds. I don't know if I personally would do it as I'm short on time at the moment and have no need for new ho...
I've done that maybe 2-3 times. At least the "initial" house, when I expanded I usually built the rooms "from scratch". Its a great feature if you want a house built fast, just pick the colour and place it :)