Finding a better way to do economic forecasting

My colleague Steve Liesman has published a report on the government's quarterly GDP report. Summed up, he found a large, persistent error in GDP between initial and final GDP reports. Not only is it off significantly, the government even gets the direction of growth wrong 30 percent of the time! Why is economic forecasting still so bad? Many feel that the tools being used to make the forecasts are simply inadequate.