If these were some magically private models that have insight into my past technical explanations or the specifics of my work, this would be a much easier bargain to accept, but usually, nothing that has been written in an email by Gemini could not have been conceived of by a secretary in the 1970s. It lacks control over the expression of your thoughts. It's impersonal, it separates you from expressing your thoughts clearly, and it separates your recipient from having a chance to understand you the person thinking instead of you the construct that generated a response based on your past data and a short prompt. And also, I don't trust some misandric f*ck not to sell my data before piping it into my dataset.
I guess what I'm trying to say is: when messaging personally, summarizing short messages is unnecessary, expanding on short messages generates little more than semantic noise, and everything in between those use cases is a spectrum deceived by the lack of specificity that agents usually present. Changing the underlying vague notions of context is not only a strangely contortionist way of making a square peg fit an umbrella-shaped hole, it pushes around the boundaries of information transfer in a way that is vaguely stylistic, but devoid of any meaning, removed fluff or added value.