If bike mfg went to disc brakes it would seem to me to be a huge improvement. Discs work better in the wet, and the biggest thing of all is your rim doesnt get ruined. Add to that the rim could be of any shape the rim mfg thot best.
I have read many cross country ride reports where rims have failed due to wear out. But if these riders had disc brakes, if they had brake trouble just changing either the pads or both disc and pad would fix the problem at a much lower cost.