Agreed. If you're using a tactic to get your way and with the assumption that you are the expert (and the other person is wrong) then you are missing out. In my experience, the best solutions came after those discussions where you get the other party to explain their motivations. The result was always better than I could have come up with myself.

When in a position of authority, I had the opposite problem: I often couldn't get people to disagree with me. This made it impossible to get to that discussion. (Maybe my ideas really were perfect, but I doubt it.)