For me the biggy is when the camera gets the white balance wrong, it is a lot easier to sort out in the RAW than the JPEG. It can be very difficult to see as well when you review the shot on the small LCD on the back of the camera.
I agree they do take up a lot of space though but given the cheaper price of memory cards and hard disks for that matter I don't see it as a big problem. Although having said that I am going to have to have a ruthless blitz on my images some time soon
It is good to see all the pros and cons being thrown in here.