Lots of room for improvement that is hard to get, perhaps. I'm most likely to leave reviews for professors if they were either exceptionally good or bad, and I'

Lots of room for improvement that is hard to get, perhaps. I'm most likely to leave reviews for professors if they were either exceptionally good or bad, and I'm too lazy to leave one for a mediocre one (the vast majority) unless I was already motivated by an exceptional one. A change in websites wouldn't change much there.