I disagree such a change would be very unpopular and unnecessary. It wouldn't really decrease the demand either players who want will still get it why should everyone as we're be punished with paying extra for the upkeep of a house. There are players who have spent a long time probably saving to get the house but they won't they would just be quiteridiculous to add a taxing to houses in order to try to manipulate people out of going for mansions.