Chuck, et al:
Although I like anodizing on all of my bike parts, I've presented my response to your Campy NR/SR anodizing "pop quiz" without having studied in advance:
Generally speaking, I think that anodizing was done to improve durability on the more highly stressed parts.
The NR/SR hubs and seatpost were left unanodized due to a reduced wear and tear on parts that receive little surface contact and only incidental dirt contact. Their relatively wide spread over the bike also allows for dramatic effect when polished (incidental advantage).
The NR front derailleur body is left untreated because it gets wear only on the steel pins. (No mechanical wear on the aluminum).
I don't know why they didn't bother to anodize the DT shift levers (presumed to be covered with rubber covers)? It is otherwise a low stress part.
I suspect that crank arms get anodized to reduce the chance of their galvanic fusing onto the BB axle. The anodizing will also reduce wear and tear due to incidental ankle and shoe bumping. Improving the corrosion resistance will reduce or eliminate fatigue-aggravating surface cracks on a highly stressed part.
The alloy SR headset might have been anodized to minimize the chance of fusing onto an unpainted steel steering tube (galvanic corrosion). Anodizing can reduce the wrench marks on the locknut and top cone.
The chainrings get anodized to improve their resistance to mechanical wear from the chain. The rear derailleur gets anodized for mechanical wear resistance (aluminum against the brass bushings); road weathering is reduced also.
Brake levers get a lot of salty hand contact, and the aluminum would start to corrode as a consequence. Calipers are anodized to improve weathering resistance due to tire throwup. Maybe the elimination of surface corrosion will inprove the fatigue resistance (less cracking) on these highly stressed parts.
Pedal bodies get stepped on and torn up with or without anodizing, so it probably wasn't worth the cost for a part that is low to the ground and stepped on a lot (implied social judgement here).
Andrew Gillis (Long Beach, CA)