It seems business is very applicable in the real world, making relationships, making the most of them. Why do more academic courses like Economics or Political Science have such a better reputation?
This difference in kind may explain some of the attitudes that are out there though. MBA's are relatively new in terms of degrees and they are much more applied than most degrees. This is simply different from what other students are working on and people tend to be disdainful of what is different, especially if it is also new. This is just an off the cuff thought, but it seems to fit.