Give me a blank Comment box when I am editing my post, below the "edit summary" field

Question

When editing my question or answer, I want a blank "comment box" under the "edit summary" box.

The edit summary field is documented by answer https://meta.stackexchange.com/a/84708/242736 to explain "what is edited" and not "why edit was done".

I want to use that additional comment box to explain "why edit was done". Other people also wanted to write about "why edit was done": Why aren't edit summaries shown? (I was requested not to write this feature-request as an answer to that post.)

It would be more convient to fill that comment while editing than afterwards. And without that comment box, readers have the time to be confused and post such comments between my edit and my comment.

For example, in some of my answers to a Tex.SE question, I have taken in account suggestions posted by others in the comments; I then added a comment to thank them, and also to let the reader understand that these comments have expired; it would be better if I could expire myself the comments as discussed in this question.

Answer 1

This request is largely made obsolete by the ability to edit posts inline, which is a privilege given at (I guess) 2k reputation.

Once you get this privilege, if you type in your comment before saving, and post it either right after or just before, while they won't be posted at the exact same time, the time difference between the two should be mere seconds.

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Mainly with regard to editing someone else' post: (old response)

You absolutely should be using the edit summary to justify your edit (i.e. explain why it was edited), if justification is required.

Note that the only people who should care about this summary are those who would be reviewing your edit and the author of the post (and perhaps people who read the post before it was edited).

If this summary might be important for a random visitor who reads the post at some point in the future, some version of it should absolutely be included in the post itself instead. But, if you think this needs to be done, you should be careful - you're likely making an "invalid edit" or a "radical change" - you may consider just commenting and letting the author edit the post him/herself if he/she thinks it appropriate.

(There are borderline cases where you may want to reply to a comment after editing - in this case it makes perfect sense to comment as well, but it should be fairly rare)