Why carbon rims?

[MikeD]

It seems now that the De Gendt crash was not caused by the hookless nature of the rims, but by fracture of the rim itself after hitting something (a rock). I was on a long ride, 40 miles in, out in the middle of nowhere and hit a pothole with my aluminum rim and the tire instantly pinch flatted and the rim got all bent up but didn't break. The tire did not come off the rim. I was able to straighten the rim up enough to complete the ride and I did not crash. Carbon fiber is not a ductile material. If you exceed its yield strength, it does not bend, it fractures.

What's so great about carbon rims over aluminum? Maybe a little weight savings? They don't work all that well with rim brakes either, and can deform from braking heat. They suck in wet weather too.