I for one would welcome an increase in moghouse size, at the moment my entire bank inventory is furniture 80/80 furniture. It's so cluttered with event furniture/other furniture that some of my friends that visit house, their computers lag to the amount of items it has to render.

I don't how hard it would be for SE, but my thought programming wise it shouldn't be that hard to just duplicate the moghouse for everyone.

For instance, you either talk to the moggle or the door to exit and there is another option, travel to floor/room 2, or 3, etc. In this way it is just the same mog house but 2 floors worth. You would only be able to view one floor/room at a time but would probably be possible under PS2 limiations since it is not altering the current moghouse in any way, just duplicating it, similar to how I suspect mog safe, satchel, and sack were added.

It would be the easy way out, rather than redesigning moghouse with doors that lead to other rooms, but at least it would increase the size of our moghouses to be able to display furniture.