When I built a custom frame as my dream/ultimate commuter, I certainly had an option to go with disk brakes. But no, I did canti/v-brake studs instead. And not even once have I ever exclaimed "Good godz, I wish I'd gone with disk brakes!" Not that the weight makes a huge difference at all, but I don't mind saving a few ounces and sacrificing overkill-level braking power.