The problem of the weight and placing of the motors. Hub motors give better performance than inboard motors but come with increased amount of unsprung mass which causes more problems on its own.
A new Hub motor which is lighter than the conventional ones. The torque and speed control is better than the other motors too at least in theory.
More space inside the vehicle which could lead to more space for batteries. The Transmission losses are eradicated. The motor works fully on programming. There is not much unsprung mass like the other hub motors.