Because I have MMO experience.
In EQ2 no one visited your wonderful instanced house , even though there were a myriad of collection items, crafted furniture and other wonders to see.
No one wanted two more loading screens for nothing.
On the other hand , in SWG there were non-instanced houses (ahhh, the wonders...) and a skilled crafter was actually meaning something,( not all crafted items were identical and also there was item decay, and SO much more), and would sell his wares directly in his home, with his vendors, and if you'd go to buy directly (clever trick to make you go visit the house), you would buy stuff cheaper than at the GTN.
The player cities would have a mayor, militia, would grow with number of citizens and would create civil galactic war drama and, yes, COMMUNITY.