Blame Mavic, they started the whole proprietry wheel thang. People were threading their fine rims to other peoples hubs. In an effort to boost sales of Mavic's (very good) hubs they started selling pre-built race wheels. There is no way you could build a standard wheel as light or aerodynamic as a proprietry racing wheel. Breaking standards means you can use straight-pull spoking, low spoke counts and funny shaped and non-ferrous spokes. And you make more money.
Mavic, youre a very naughty boy.