I am very sympathetic with Athreya (a Fed economist) who says that it is hard to believe that economics bloggers provide any useful information to the public, since the issues are too complicated for the public to deal with. I personally think think they are too complicated for me to pass judgment on, after having devoted nearly half my life to studying economics, so I agree that it is silly to think the public can figure this stuff out. Not just on issues of macroeconomics, but on most issues of economic policy.
But I have two important caveats:
1) In a Democracy, we need accountability and cannot delegate all decisions to experts. Maskin and Tirole have a nice game theory paper on this. Also, John Dewey makes the nice point that since artists can convey very complicated ideas and emotions to the general public, why can't social scientists learn to do the same?
2) While there is little hope for the public to understand the technical science behind economics, there is the possibility as Cowen suggests for people to understand the underlying intuittions. James C Scott calls these distinctions techne vs metis and articulates very well for the importance of intuition.