I think there's another reason related to your a) and b) why companies hire management consultants, particularly in less dire corporate situations than you desc

I think there's another reason related to your a) and b) why companies hire management consultants, particularly in less dire corporate situations than you describe above. I think a lot of management consultants' work comes from boards or division managers who have a difficult decision they know they want to make (fire workers, spin off less successful business units), but need an "impartial" "expert" to agree with them to help justify it. The company asks only the questions they want the consulting company to consider, they get the answers they want, and they have an "independent" (and expensive) second opinion that covers them so they can go ahead with what they knew they would do in the first place.