I think if they were to do this, and they insist on sticking to the awful ward system, it should be a combination.

You pay one time, something like $20 to unlock access to a house on another character (assuming one of your characters has a house already). Upon actually buying a house on that second character (since, you're still going to have to fight for it, you assume the risk), your sub fee goes up by $1 for as long as you keep that second personal house. This way, people that want an extra house can get it, while also funneling in more money to ideally help pay for more wards to open, or for ff14 to be able to fund a way to fix the system as a whole.