The GMAT and GRE are indicators of performance in key skill areas that are required to be successful in advance degrees of study. The questions are specific to core competencies that should have been mastered in order for the student to continue advanced studies. Those that score exceptionally well on the tests are more likely to be successful. Plus, it gives the review board an unbiased method for selection that puts all applicants on an equal footing. This is necessary because curriculum at universities varies across the board. Your “A” at your school may be the equivalent of a “B” at another school. This process makes all things equal.

I think it is, if for no other reason than that schools need a way to compare students from different schools. Some schools practice serious grade inflation, some don’t. Also, there needs to be an equalizer for the reputation (or lack thereof) of the different undergrad schools–it isn’t necessarily fair that a Harvard undergrad with a 3.5 beats a State U. 3.5, the State U kid might be a better match for grad school. Then when you get to the elite programs, there are way too many qualified applicants for the number of seats available, so the GRE helps differentiate them.