I think the real reason why people like this author don't like Gladwell is because he bypasses this writer's academic community to deal directly with the masses. He gives normal people what they want, makes them feel smarter and more confident analysing the world, and, most insultingly, does it without respecting the rules of conduct developed by academics. This really stings because the community itself has failed to communicate with normal people, but its members still feel like they deserve to be listened to because they know they are right. Its playground jealousy - they can't accept the fact that they don't know how to compete with Gladwell, so they sit around wagging their fingers about the hidden dangers of his writing.
"Hidden dangers"? The review doesn't say Gladwell is dangerous, just that he doesn't actually PROVE anything, but people take his claims as if their solid & settled science. There are scientists & researchers who can communicate clearly — Einstein did, Bill Bryson does for astronomy, etc. — without going too simple.
