The social capacity of this mansion is not limited by the size of its kitchen, or of its ballroom, but by its bathroom--specifically, the fact that there's only one. To cut down on the inevitable line, the host would have to make the upstairs accessible, which has security problems all its own.
To give the designers some credit, though, it is a decent bathroom, as far as they go: all the required fixtures, stylish marble, decent lighting, plenty of room between facilities and the door leading back to the hallway.