I think there is an over-simplication of the situation only in that IT staff and consultants are sort of lumped together. There is one aspect of being a consultant that is overlooked in the article - customer service. For the consultant, there is often not the loyalty to the other IT folks at the client site, but to the one signing off on the project.

I have been blessed to have customer service drilled into me as a consultant by one of my employers from the top down so that when I began a job as one of the IT staff, I identified my manager, who was not technical, and the other managers that I supported as the client. The idea of striving to add value as a consultant is true and I tried to bring that to bear as one of the IT staff.