A lottery system wouldn't reduce the level of frustration for players since it would increase the competition for an open plot and everybody except the one lucky player would still be left wanting.

Right now I suspect few houses are getting a chance to devalue more than once before they're purchased. Changing how houses devalue still does not make more houses available for those who want houses.

If you're going to insist on dreaming up ways to change the ward system so that more houses are available, request SE to implement a monthly property tax that must be paid or the house gets demo'd. A lot of players are going to lose interest in owning a house if they have to pay gil monthly in order to keep it.

Even better is to give up trying to find ways to change the ward system and focus requests on improvements to the instanced housing system (apartments) that would make them a more desirable alternative to owning a house.