The main two reasons why people buy guild houses is (a) they are larger than houses, and (b) have much more grass to create a farm. Player houses are meant to be smaller, and have little to no grass. In the house template with the most grass, the swamp house, the grass is scattered, so it is inefficient to farm. The new castle house template had over twice as much grass + bushes as any guild house. Which means means no one would buy guild houses anymore...