In Simon's words:
"It is hard to get academic macroeconomists trained since the 1980s to address [large scale Keynesian models] , because they have been taught that these models and techniques are fatally flawed because of the Lucas critique and identification problems."
"But DSGE models as a guide for policy are also fatally flawed because they are too simple. The unique property that DSGE models have is internal consistency."
"Take a DSGE model, and alter a few equations so that they fit the data much better, and you have what could be called a structural econometric model. It is internally inconsistent, but because it fits the data better it may be a better guide for policy."