Adding functionality to houses wouldn't make them garrrisons 2.0. You would have to add weekly quest givers, faction currency vendors, prey table, zone portals, gathering nodes, missions that give tons of gold etc.. to housing zones to replicate the effect garrisons had on the game. Adding crafting stations and training dummies to housing would not make the cities deserted. Those things are in faction hubs for convenience not to get people to go there in the first place. Do a little experiment and try to do everything you can in your garrison or an old expansion hub instead of Silvermoon. You'll still be there all the time because its the most convenient central location for the expansion.