For one particular application, I want to use a rubric as a marking key that adds marks up automatically, and to record all of this in a nice auditable way for external examiners. This would be incredibly helpful for marking and for QA, but worthless (and possibly confusing) for students. Rubrics are used to communicate standards and expectations in advance of an assessment, and giving detailed and specific feedback, is extremely valuable. I routinely use rubrics in this way.
Since this isn't what rubrics are designed to do, I'd like to request a purpose-built tool that allows instructors to refer to an answer key in Speedgrader during the grading process.