If I'm talking to a friend I want them to be themselves and genuine. Having someone else compose a message for them, AI or human, invades my privacy and tells me that they don't want me to see who they genuinely are. Talk to me like you normally do. Don't paraphrase everything you want to say through a third party. We're not strangers, there's no need for everything to be professional. I'm friends with YOU, and I'm talking to YOU. Don't pretend to be someone you aren't.
To me this is less about AI vs Human, it's just the fact the friend isn't being genuine.