Schools are free to give preference to an applicant's willingness to work in underserved areas. They just can't use race as a proxy for an applicant's "likelihood" to do that (or anything else). I admit that race is "relevant" to a lot of things, but 14A forbids states from denying a benefit on the basis of an applicant's race.
Today the NY Times has an article about how Rice Univ uses code words to perpetuate racial discrimination (under the guise of affirmative action). I found the Rice attitude offensive. They believe that they are circumventing the law using phony gimmicks so they can continue to get $45M/yr from the feds and continue racial discrimination.