I agree - nobody needs to be a crack in any area, but whoever will take decisions needs at least a base understanding of the theme to judge the validity of the foundations on which those recommendations are based upon; anybody could be a manager if blindly following recommendations by subordinates would always end up in the best choice.
EDIT: but "Gpetrium"'s statement is actually still correct ("a department can still be functional and even successful if their boss listens and applies the ideas offered") - maybe from this perspective it's more a "must" for a successful manager, but, after the "listening" comes the "judging" and that MUST be based on own know-how.
EDIT: but "Gpetrium"'s statement is actually still correct ("a department can still be functional and even successful if their boss listens and applies the ideas offered") - maybe from this perspective it's more a "must" for a successful manager, but, after the "listening" comes the "judging" and that MUST be based on own know-how.