Why economists failed to foresee the Great Recession?

Raghuram Rajan, whose comments I have blogged about earlier only with appreciation, and who is fast becoming one of my favorite commentators on economic matters (the Indian connection is a bonus!) continues to think about why economists failed to anticipate the Great Recession--the question that bugged everybody from the Queen of England to my mother, who asked me the same question as the crisis started unfolding:

three factors largely explain our collective failure: specialization, the difficulty of forecasting, and the disengagement of much of the profession from the real world

Hey Professor Rajan, can you condense these into a crystal clear bottom-line that in very simple words will offer the explanation to my mother and the Queen of England?

many simply were not paying attention!

There.  That is one hell of a blunt, honest assessment!  Thanks.

ps: of course, the topic of how economists screwed up (and continue to do so) is not a new topic; this is an example