It has been brought to my attention by one of our moderators (here) that they are unable to enter a free-form response to comment flags.
This is unfortunate in some cases where there is e.g. a pattern in a number of flags, or where it is obvious that a reply is in order -- notably when someone uses the free-form flagging reason on a comment.
I think this should be changed at least for the last scenario: What use is there in leaving a free-form flag if the response isn't free-form?!
Implementing this feature request will make it easier for moderators and users to interact without resorting to meta, chat, or e-mail. If those measures are somehow deemed necessary by the moderator, it also provides a natural platform for them to indicate this.