I was surprised to learn that the student body is now more diverse in terms of “race and ethnicity” than it was 15 years ago. The surprising thing is that race is mentioned at all. "Race" in America is determined entirely by one's external appearance – skin pigmentation being the most salient feature. Difference in skin color is hardly a marker of diversity.
The only thing that makes sense of "diversity" is what is internal to the person, not external. Only differences in ethnicity provide meaningful diversity. Back in the old days, I felt our class was sufficiently diverse – we had "jocks" and "grinds," rich and poor classmates, evangelicals and atheists, extreme conservatives and extreme liberals. These are personal and cultural, not racial, differences, and adding in students of a different “race” without a differing ethnicity may look good on paper, but does not increase real diversity.