The housing system indeed is awesome, the bad is that have nothing much to offer to the players but a place to hangout with friends or personal storage.
What would be nice is if the system get a revamp, like for example:
Remove the need of setting passwords, it is really annoying, but instead be able to choose who can enter the house, if Guild mates, Friends, party members or anyone can join (and look if the person is on the group the player allowed through sql).
Allow the player to choose if will spawn in the house before going to the last place the player visited (upon logging in, be teleported to the house, and upon leaving through the house portal, be taken to the point the player were before).
Implement new functions, like have a personal store, where house owner can sell stuff by their own price (without taxes), and other players can check through the house warp.
Another thing that would be interesting is if monsters attack the house (if there is someone else than a visitor outside the house), the difficulty of the monster and quantity could be based on number of players.
Be able to make a feast for your friends and guild mates, or just random peoples, to celebrate something and give hellatons of buffs that lasts a few hours.
Several things could be implemented or changed to make the housing system more interesting.