Grades represent levels of mastery of the material relative to other students. Grading systems vary from one institution to another. They seem relative. We need to acknowledge that grades do matter to students, whether we want them to or not. Graduate school admission, for example, is very dependent on grades.
Grades represent demonstration of mastery and independent thought.
People liked the narrative aspects of the Learning Evaluations. The more written feedback students receive, the better. It is not always necessary to measure what students learned, but in some ways, grades reflect the work world. We don't really want any grade distribution standards. The grade distribution seems to flow naturally.