If this was a F2P game I'd see the argument for it. But it's not. We pay a monthly sub to play, and already have to fork out money for extra storage. I would not be okay with paying even more again for housing.

I don't think the issue is SE not having the money. This is probably a time vs profit issue. The company likely feels all the time that would be required into making enormous changes to the housing system wouldn't be as profitable as doing other content in that time instead.