R2R cuts spoke count by 2, resulting in only 2 spoke ends instead of 4.
Better aerodynamics: smooth integration of the spoke to the hub flanges
Lighter: carbon spokes are lighter than alloy ones
Stiffer: unidirectional carbon fiber spokes have agreater resistance to traction
Stronger: since R2R reduces the number of spoke in half, it cuts the chances of spoke breakage as well.