A grade from UCB or any theater, does not indicate my level of improvisational skill. Grades are subjective from teacher to teacher. Unless they really know you as an improvisor, there really isn't, in my opinion, any proper scale to determine you're improv ability. However, you can determine a grade by class participation, tardiness, etc. etc. As someone mentioned before - it's an art form. So of course everyone will have an opinion either way. Religion, art, politics - everyone has an opinion about it. Grades submitted for an art form are "subjective grades" or "opinion based grades". It's not like taking a math test with a formulaic system of answers - it's art. There are many different answers.
I didn't voluntarily spend $325 a class because I want to get on a Harold team or because I want to get a "grade". I took these classes because a) I made some wonderful connections b) I have a really interesting new set of skills and c) it's FUN.
oh and an added d) classes are tax-deductible. But everyone has different reasons for these classes.
And for my staple comment I always make after a discussion like this, "Who cares? People are dying."