Years ago, in a postmodern rhetoric class I was taking, we were asked to watch one of Bill Clinton's speeches--thankfully not the infamously long one from the DNC Convention in 1996.
Instead, Clinton was talking mainly to the camera, but was at a podium. And he was gesticulating with his hand.
You've seen him do this: remember his famous line "I did not have sex with that woman"? Do you remember his hand? It was in a fist, sort of, pounding with every third word.
That fist, though, is a trademark of his: his first knuckle of his index finger points outward just a bit. It's as if he used to point with that finger, but was told by a communications adviser to stop pointing at the camera--the audience would take that as an affront. No one likes to be pointed at.
So now he makes a fist at us?
Rhetoric involves all of the elements of a communicative act, not merely the words in a speech. Who you are, what you do, what you look like, what tone of voice you use, and what gestures you use are all part of it. In Ancient Greece, and again in the Renaissance, when students were still taught rhetoric as a skillset, one's gestures were a part of that training. How one stood, what one did with one's hands, even how extended or forceful one's gestures were, were all part of understanding how to communicate clearly and effectively. Some Renaissance rhetoric books even had drawings, demonstrating how far one's hands should move and in what ways to convey specific emotions.
Not recognized the impact of one's hands, one's stance, when talking to an audience fails to realize that the audience will react to more than the "substance" of what one has to say.
Bemoaning the focus on "style" or appearances is all well and good, but it's still not going to stop the audience from making assessments of the person--and, by extension, that person's message. If one wants one's message to be heard, then the rhetor needs to be sensitive to the cultural expectations of the audience--including those expectations of appearance and style. If the audience has to spend effort to ignore the rhetor's poor cultural signals, the audience will either dismiss the rhetor as incompetent/irrelevant, or the audience will judge the rhetor as misguided/untrustworthy.
Seriously, then. Even if you did have sex with that woman, don't go making a fist at us. We notice: maybe slowly, but we do. And we don't want to be pounded on.