I've said and I'll say it again, the primary cause of the economic mess was regulatory and oversight failures. See Washington Post, Greenspan: 'Crisis Broader Than Anything I Could Have Imagined', in which Greenspan admits that the failure of the expected self-regulation represented "a flaw in the model" he used to analyze economics.
Translated from Greenspan-speak he said he now realizes that the fox shouldn't be left to guard the henhouse.
Thanks for the insight. Someone should revoke his government pension.