Why Isn't "New Keynesianism" Called "New Pigouvianism"?

Axel Leijonhufvud had at least this part right decades ago:

"That a model with wage rigidity as its main distinguishing feature should become widely accepted as crystallizing the experience of the unprecedented wage deflation of the Great Depression is one of the more curious aspects of the development of Keynesianism, comparable in this regard to the orthodox view that 'money is unimportant' - a conclusion presumably prompted by the worst banking debacle in U.S. history. The emphasis on the 'rigidity' of wages, which one finds in the 'new economics', reveals the judgement that wages did not fall enough in the early thirties. Keynes, by contrast, judged that they declined too much by far. It has been noted before that, to Keynes, wage rigidity was a policy recommendation and not a behavioral assumption." -- Axel Leijonhufvud (1976). "Keynes and the Keynesians: A Suggested Interpretation", American Economic Review, V. 57, N. 2: 401-410.

Lots can be argued about in Leijonhufvud's interpretation of Keynes, and Joan Robinson came to argue about it.