I get what he's frustrated with. Hell, I live in the Washington area. I am surrounded by what he's frustrated with. And I'm frustrated too, not the least because there is cause for concern about public debt and public spending that is in my mind most responsibly communicated by relatively centrist people like Bob Reischauer, Christina Romer, Gene Steuerle, and the whole crew at CBPP that get drowned out by the sorts of people that Krugman is frustrated with.
Krugman is mad at the pundit types and the politician types that like to appear reasonable. That's why he calls them "centrist".
But they're not.
Across the ideological spectrum journalists and politicians love to moralize about debt. Krugman just complained about Jon Stewart doing this in the discussion of the platinum coin (which I oppose for political economy reasons - not for the first approximation macroeconomics of it). Is Jon Stewart a centrist? Of course not - he's a liberal. I'm sure Rachel Maddow has a ton of screeds about how bad the debt is, citing the wars and the tax cuts too.
It has nothing to do with centrism and everything to do with the fact that these people (journalists and politicians) don't take a scienitific approach to the economy the way analysts do.
Among analysts the only real problem is the conservatives (and even some of them - I'm thinking of conservative New Keynesian types - aren't all that bad). Centrists and liberals in the analyst community understand what Krugman is frustrated about here and they even understand how to have responsible concerns about the debt without flipping out over the sticker shock right now.
I think Krugman is targeting the wrong people and painting himself as being more far left than he actually is when he complains about centrism. The distinguishing identity of these people is that they are politicians (Simpson, Bowles, the entire Congress), policy entrepreneur types (David Walker, Pete Peterson) or they are journalists. It's not their ideology - it's their method. And their method is not scientific, it's moralistic.