School, and public education in general, depend upon grades to motivate "students." Without grades, students have no motivation to work beyond the bare minimum required to get a GED. This is partially due to the fact that from the perspective of the public school system, learning stands in the way of the objective of indoctrination. Thus, if the motivation afforded by grades is removed, why does anyone do anything? Any actual education is quickly quelled by activist administrators and politicans, leaving only the promise of a carrer as reward for the experience. If these carrers are not tied to grades, then what difference does it make if a student skips class, does drugs and either gets knocked up or knocks someone else up?
This trend continues into college (if one decides to enroll), despite that actual learning is occasionally encouraged. Many students are too used to the idea of schooling exclusively for the ends of a job to ever see any broader purpoes to education. Grades continue to be the sole motivation for work to those unable or unwilling to partake in the braoder system that is college.
That's why there is so much danger in the fact that not only were Bush and Kerry not star students, both had below average grades. Without the motivation afforded by grades, and with most students ambivilent towards self-education, there no longer exists a system by which an educated and critical populace can be developed. It is unfortunate that things are allowed to develop this way, but perhaps there is hope here, in the blogosphere, in that enhanced global communication and awareness might provide the spark needed to encourage criticality, and thus education. Time will tell if this optimisim is misplaced or not.