There's really no real need for a tax to be implemented for player housing. ESO has player housing and does not tax players if they purchase a house there...nor does it take the houses away from someone if they take a break.

Perhaps instead of finding ways to punish people lucky enough to own a house in FFXIV...we could instead push the development team to actually make it a part of the game that is available to everybody? It can be done. Rival MMO's have done it. Some of which are even older than FFXIV itself.