If useful doesn't equal accurate then you have biased your map.

The most useful beliefs to have are almost always accurate ones so in almost all situations useful=accurate. But most people have an innate desire to bias their map in a way that harms them over the long-run. Restated, most people have harmful emotional urges that do their damage by causing them to have inaccurate maps that "feel" useful but really are not. Drilling into yourself the value of having an accurate map in part by changing your emotions to make accuracy a short-term emotional urge will cause you to ultimately have more useful beliefs than if you have the short-term emotional urge of having useful beliefs.

A Bayesian super-intelligence could go for both useful beliefs and emotions. But given the limitations of the human brain I'm better off programming the emotional part of mine to look for accuracy in beliefs rather than usefulness.