Will this version let me compose text-only messages by default while still being able to switch to a HTML message when needed? You used to be able to shift-click reply to compose as text but that that stopped working in a previous update.
Edit: Apparently I was wrong and the replacement "Smart Reply" button does show up, but only sometimes depending on context. Since Thunderbird only shows it selectively now, I did not see that when I was checking before.
So I withdraw my criticism about removing functionality, and I replace it with criticism of changing user settings during updates, replacing a well-established feature with a subtly different one, and hiding controls that are currently not applicable rather than showing them as disabled. The fact that this comment thread exists is a pretty good demonstration of why these are bad ideas.