If you're unsubbed for so long that your house demolishes, were you even using it really? Did you derive any value from it? What about your neighbors who saw a vacant house with nobody living in it for so long? Player housing should go to players who will actually use it, both in terms of giving active players a chance to enjoy the housing system and to make neighborhoods more active and vibrant.

Also you're not actually losing much when your house explodes. You keep all your furniture and 80% of the gil cost of the plot.