I agree with all arguments of the OP. Housing and related cosmetics, collectibles and achievements, along with some utility is a whole mini game that keeps players invested in other games that have it. Many players only play for their houses in SWTOR, called strongholds there.
I don't know what is Blizzard's hesitation for adding and improving features that are very successful elsewhere. All they do instead is layering overproduced power increase systems on top of each other that keep being I'll received.