If Harvard graded on a curve, such that half of their students—who presumably got straight A's in high school—received a C or below, would that be more fair? Would it be a better representation of student performance?
I suppose the answer depends on the purpose of giving grades. If the goal is to see who outperformed who, Harvard's average GPA is a major problem. If the goal is to see who learned the material, then Harvard is providing an excellent education.