I know! I mentioned that. That's what I meant with "that you always have to bring the cradle with you" if you want to use that option, because there's no ethernet port on the Karma itself.

Also, I prefer to use firewire/usb2 whenever I can, because of the speed advantage. OK, so that might be a detail, but I like my file transfers as speedy as possible. The difference in speed between USB2 and 100baseT ethernet is still substantial.
Also, not everybody's pc has got an ethernet card in it. (ok, so those ones are getting rare, especially the ones that DO have USB2 )

When I think of the ethernet port on the Karma, I think more along the lines of music streaming than file transfer. I don't know why exactly, but the forementioned reason of always having to bring that cradle with me if I want to use the ethernet port is probably the biggest reason.