Comments on Stephen Grenville “Why forecasting has broken down”, 10/01/2013, http://www.businessspectator.com.au/bs.nsf/Article/Global-economy-fiscal-policy-forecasting-models-ec-pd20130108-3R4MS?OpenDocument
I think the reasons why those international forecasters consistently got their forecasts wrong you mentioned are correct ones, though there might be more than those.
I think there might be a different effect of globalisation on the aggregate demand and supply of an economy.
The conventional frameworks for macroeconomics may suffer from lacking a closer look at the effect of globalisation on the supply side in the context of a serious supply side shock in the wake of the GFC and the ensuing various other related government debts and fiscal problems.
Let's say various macro policies do have an effect on increasing the aggregate demand of an economy, but that may not necessarily restore the domestic supply side when international supply can substitute domestic supply due to their advantages in being unaffected by the supply side forces that exist in the more advanced economies such as the US and EU.
This increased effect of globalisation and trade substitution on the side supply may suggest that the full recovery of the advanced economies to their normal growths may take longer time even though the macroeconomic policy particularly the monetary policy is much more accommodating now as compared to the 1930s.
Unless the governments can come up with new ways to restore the domestic supply side of an economy, the road to recovery will be long and hard for those economies.