ElectroVlasic, It's not the MBA it's self the people are slagging off, it's the fact that, in most cases, they are given management positions immediately after they get it and have no experience of how that industry functions.
In the old gays even the bosses son started as "tea boy" and worked his way up through all the departments so that he knew exactly who did what, how and why.
Yes, this is how "Roger the Cabin Boy" worked his way up, right?
While I've seen your point being made, I've also seen various people's biographies posted, and when they've listed having an MBA, the resulting comments are that the person must be an incompetent idiot, etc.
I agree that one must gain the prerequsite experience before being put into positions of authority. If they are putting newbies into positions of authority, then they get what they deserve.
Luckily, in my company, most people I know who have an MBA only decided to get it after a few years or more in the trenches, and usually end up getting it by taking classes after work, so their experience builds as they are gaining the MBA.