Whereas ethics is now taught as a system of rules, rather than a fundamental and intrinsic part of being persuasive as an advocate. Which l don't think is helpful.

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.'