One should also consider that forecasts are tailored to their audience:www.tinyurl.com/wetbias
(A NY Times article)
In what may be the worst-kept secret in the business, numerous commercial weather forecasts are also biased toward forecasting more precipitation than will actually occur. (In the business, this is known as the wet bias.) For years, when the Weather Channel said there was a 20 percent chance of rain, it actually rained only about 5 percent of the time.
People don’t mind when a forecaster predicts rain and it turns out to be a nice day. But if it rains when it isn’t supposed to, they curse the weatherman for ruining their picnic. “If the forecast was objective, if it has zero bias in precipitation,” Bruce Rose, a former vice president for the Weather Channel, said, “we’d probably be in trouble.”
The analogy for financial soothsayers is probably that they are simply wrong. Nothing intentional about that.
But, I believe there is a "bear bias". People are happier with down predictions that do not happen than they are with up predictions that do not happen.