When an instructor writes long comments (I have seen 10+ paragraphs) in Assignments for an assignment that is linked to the Gradebook, all the comment text is displayed in a narrow column. This means that the height of that row in the student's gradebook view has to be as tall as needed to accommodate the feedback. Since the Gradebook also can't propery handle the rich text comments from Assignments, the feedback as it appears to students in the Gradebook can become a giant blob of text without even paragraph breaks.
We have had instructors complain that it makes their carefully written and formatted feedback in Assignments seem unprofessional when view by students in the Gradebook.
At the very least it would be good in the students' view of the Gradebook to add a CSS max-height of a few hundred pixels and overflow:auto in the comment table cell so that the individual comments could be scrolled through if they get long. This would keep each row from exploding to be thousands of pixels tall.