Nobody who ever read up on the mob a bit claims Gotti was a great boss.
On the other hand, every average-Joe-nitwit who speaks gangster lingo to impress his local stoner buddies worships that iconic Gotti black-and-white courtroom picture like the North Koreans worship the Great Leader Gold Statues.

And let's be honest; there's a lot more of the latter category around than there's of the first. When we're talking from a "popular culture" point of view, Gotti definitely qualifies as overrated.