It's almost mandatory. If you truthfully say that your opener does not contain any "throw-away" items, nobody will believe you, so you might as well include some.
There's also a psychological value in letting the other side win a few points if it helps you win the match. They have to "save face" too, and a cave-in won't do it for them, or for a mediator. Ideally, each "trade" you make should be accompanied by loud groans and quiet grins.