What is evidence that style is more important than the central argument and evidence in politics, in Julius Caesar?

In Julius Caesar, several characters deploy arguments using persuasion and the illusion of merit to convince others of the validity of their position. The merits in terms of substance are open to debate.
The first character who uses these techniques is Cassius. He knows that Brutus is the key person to sway others to join the conspiracy. Both by praising Brutus and his family heritage and by implying that Caesar has a swelled head, he encourages Brutus to think Caesar does not deserve to be a ruler ("colossus"). By appearing to put himself down and associate Brutus with that inferiority, Cassius basically guarantees that Brutus will go the opposite way to prove his valor. Cassius says "the fault . . . lies in ourselves that we are underlings. . . ," knowing Brutus does not see himself that way.
After the assassination, Mark Antony, who did not join the conspiracy, is distraught. He knows, however, that he has no time to succumb to weakness. He must get the Roman people on his side right away, before Brutus and company get a chance to convince them that they did the right thing. Antony not only convinces Brutus to let him speak at Caesar's funeral, but he manipulates the crowd and ultimately riles them up against Brutus's gang by appearing at first to admire the conspirators. After praising their "honor," he turns the tables and goads the populace into rejecting them.