SWTOR's world is too small to allow player house. There will be a lot of QQs that players can't find land or the location them like to build their house. (As EX-UO and SWG player I know it all too well.)
Well seeing as the game has instanced areas you are wrong about that. They could easily make a building not being used into an instanced home. If you wanted to invite people in you send them an invite just like in STO. No one can get onto your ship unless you allow it.