I think issue #426[0] would be sufficient, since it would allow for editing after the command is finished. I understand that it probably won't happen any time soon, but embedding a full terminal emulator in Eshell is the thing that's got me staying on EAT right now.
Ghostel looks really nice though!
Noted.
I didn't even think of the use-case that then you can edit output from finished commands in the scrollback. But it makes sense and is another +1 for that feature request.