Why are MBA grads seen as arrogant?

MBA is often caricatured as management by analysis/spreadsheets etc, and those without MBAs are often quick to label newly minted MBAs as arrogant ivory tower residents, who expect things to be done by the book. While the two years of solving business school cases would have taught MBAs about incomplete information/complexity etc, the extra curricular activities would have shown value of organizational dynamics, interpersonal relations etc. So what would make others perceive MBAs as arrogant? That is a question which has often puzzled me. From my interactions with alumni, those with work experience and others, the points I would think of are below

1. Expecting best practices:-MBAs are trained to look for the best way possible, and not the most practical way. Hence when they see old(but tried and tested) practices on the field, the initial tendency would be to critique those fuddy duddies, who naturally resent the new person critiquing without showing proof of concept/pilot of his new idea
2. Overconfidence:-Getting high grades in classroom/being best at case solving does not speak anything about ability to execute. But people who forget that aspect, are soon brought down to earth when their textbook solution fails at getting win-win, from people who resent it. 
3. Too much respect for paper qualifications:-On an average, the MBA with a graduation degree, would be more qualified(and from better known colleges) than the persons he interacts with. Hence, the feeling of superiority may remain till he realizes that the high school pass grizzled sales veteran knows more than what Kotler textbook would ever teach! 

I guess these are the 3 main things. Would welcome comments for any others!