Q: Why does lighter unsprung mass from carbon ceramic rotors matter?

Unsprung mass is the weight the suspension has to control, wheels, tires, and brakes included. Swapping heavy iron rotors for carbon ceramic drops that mass and lowers rotational inertia, so the suspension reacts faster over bumps and the car changes direction with less effort. You feel it as cleaner turn-in and a chassis that settles sooner over rough sections, on top of the obvious gains in heat capacity and fade resistance.