You're not alone in being annoyed OP...
Adding housing in Ishgard and letting couple share houses is not a solution to the problem. Making a house shareable by up to 5 people - why not form a FC?
The only solution acceptable would be one that makes it possible for literally every active player to purchase a house (assuming they managed to earn sufficient gil to finances it).
Incidentally, if housing were available to every player, I imagine the market for crafted furnishings and other items would become far, far, far healthier.