There is a running theme that MBA's destroy value. One recent post referred to them as "MBA Monkeys". There was a recent study that said MBA's underperformed non-MBA's.
Some of the methodologies taught in business school probably stunt creativity and put focus on the wrong things. These methodologies were supposedly tested in the business world and are built into a teaching curriculum, but turns out these methodologies weren't so great after all ... unfortunately they are now codified.
That said, do I think MBA's destroy value? I know some do, but more often than not I think these people would have destroyed value even without their MBA's.