Unless there is material loss (change of shape - larger gap)I wouldn't worry about what the rotor tip or distributor contacts look like. Believe me the electricity doesn't.
The problems with caps and rotors include severely burned contacts (causing larger gaps), carbon tracking (which provides lower resistant spark paths), and in the case of rotors; high voltage shorts to ground through the rotor shaft.
Bosch Master, ASE Master, L1
33 years MB technician