I absolutely agree with you. The appeal to ethos (of the trier's of fact) is a strong emotional strategy. It is one of the main linguistic strategies I look for in identifying deceptive texts. 'Believe me, I'm honest, I have the expertise, and this is the fair/honest/best decision you can reach.'

But in oratory, the pauses, the gestures, the tone (none of which can be conveyed in text as successfully) are all a part of the performance. Fir, indeed, it is a performance and, done well, is incredibly strong.

100%. You see that a lot in opening speeches. There is usually something in an opening speech that will indicate that the advocate is honest, fair, trustworthy, educated and/or a person of integrity. It was considered a key objective of an opening speech - for the advocate to establish their ethos.