The meeting is your best form of communication with your client, especially if they are physically face-to-face. It helps you set your pieces down the right track, ensuring you and the client are on the same page.
If the meetings are with agency directors, the outcome should be similar. Communication lines are opened, goal is clearer and better defined.
It also depends on personality types. Sometimes, the meeting is simply to reinforce a director’s idea or belief.
Even in those instances, you are doing your job well by just attending, even if it feels like all you’re doing is listening to a prepared speech.