Built in Failure

I've often wondered why Paul Krugman has never been part of government. Newsweek has done a cover story on him that answers that question.

Regardless of political ideology, whether Republican or Democrat, there has to be built in failure to some degree. That is why people like Krugman are always on the outside, criticizing the in.. while being right pretty much 100% of the time.

You'd think it would be obvious that Krugman would have been a much better pick than Geithner.... but why has Krugman never even met Obama, when even some of Obama's most harsh critics on the right get invited to cocktail parties?

Pop quiz; can you tell me why the built in failure is necessary?