The big problem with Player Housing is pretty easy honestly...
This community has a HUGE COLLECTIVE SHITSTORM anytime a microtransaction is introduced..and if there is player housing there is going to be Microtransactions...TONS of them. Blizz will give you some generic stuff for gold or farming..but lets face it this will be an excuse to monetize the ever living FUCK out of it.
I mean every single MMO with housing of some sort these days has microtransactions attached to it. They will be there, people are going to be PISSED that they exist, people will see them as mandatory and blizzard is uber greedy. To make things worse I'm pretty sure token prices are going to skyrocket with them.