show one's face

Is it a courtesy to the speaker to show one's face in the audience, as if one were there in person, or is it considered good manners either way?

“It doesn’t fit in with our open society. To show one’s face is crucial for communicating, for living together in our society and keeping it together.”

“In the areas where it serves a function to show one’s face, we want to make it a rule . . . and this means whoever breaks it must feel the consequences,” he added.

Also it is important to show one's face to verify identity for security reasons.

To show one's face outboard, was then an impossibility; the gale swept before it a body of snow higher than our trucks, and hid every thing a few yards off from sight.