I wouldn't necessarily be against a more involved housing system, but I would actually want it to be instanced. Ever played UO? Houses on every tiny bit of open space gets old fast...

Special zones for it could work but after the charlie-foxtrot of FFXIV housing, I don't trust SE with it XD

And, anything but instanced housing will make future server merges very very messy...

Mog garden thingy is pretty neat. Maybe something that grows on that, with some customization options?