Teachers should be able to click on the individual student name from the gradebook and then change grades and add comments from the Students Grade Page (which shows all assignments from that one student). The teacher already gets an overall sense of the student's progress from this page the added ability to comment on the missing assignments, and add late assignment scores would be beneficial. If a student has a lot of missing work, there is no scrolling back and forth etc as there is on the Gradebook page.
There was a similar request: Modify student grades in Individual Gradebook View but the solutions given were not ideal. Speedgrader does not display all of a student's grades and the current Individual view in Gradebook is cumbersome and not very intuitive.