Supposedly they're working on a new system ("Housing Mirage") that would allow players to select the size of their house interior if they get it to work. That would help make the small plots more desirable if it happens.

Source is the live patch note reading for 6.5 but it's JP language only - the information was being shared by a few unofficial translations. Perhaps they'll share more info (or at least confirm what was said) at the EU FanFest this weekend.