It's not because business has good advice for him on economy policy. Some of its advice might be good, but most of it will take the self-seeking form of "please subsidize me in the following ways", and be bad. Cordial relations with business are desirable mainly because the country does not want to see its president at war with its CEOs. In other words, better relations with business are needed to restore the president's popularity; the more popular he is, the more he can get his way with Congress.
So I argue in this column for the FT.