I guess I would have to say that disc brakes make a hell of a lot more sense than going to 12 speed clusters in the rear. My main reason for going to discs remains the fact that it is engineering excellence NOT to wear out something as important as rims. Separating braking function from the rims allows rims to be designed for strength, weight, and aero considerations. Disc also provide a safety consideration, as on long steep decents rims will not heat ups and blow out tires.