I just did some more research on how this actually works. Either the stator or the rotor has to be rotating mass, because if it's not attached to the wheel it can't drive anything.
The main thing that bothers me is the unsprung weight. If they attached the motor to the chassis and had a short driveshaft connecting to the wheel hub, the unsprung weight would be even lower then a normal vehicle's (since they don't have brakes).
It probably wouldn't be worth the added complexity and reduced space in an economy car, but this is supposed to be a sports/GT car. How well is the suspension going to react at 200km/h with those big heavy motors in the wheels?