I'm not 100% sure how KERS (Kinetic Energy Recovery System) operate, but as far as I know in formula one the unit is located between the engine and the gearbox. This would reduce the requirement for the engine braking (which is a loss of energy) and utilize the generator to slow down the vehicle while storing useful energy.
If you are thinking of putting a generator on the wheels together with brakes (for safety) then that energy could only be used during ground operation. Energy storage would also consume a fair bit of weight that could be used as a payload.
If you use stored energy to be used for propulsion on the ground, I’m not sure the amount of stored energy from the brakes would be sufficient enough to taxi the aircraft.
It might be a good idea to use the electrical energy on the ground to provide electrical power to instrument, but during taxiing energy is provided from the engine and on the ground from GPU.
Overall what I’m trying to say is that I don’t know how KERS could help the aircraft.