The underlying assumption is that racial diversity translates into diversity of experience or perspective, and that all people of the same race share common interests or cultural traits. This assumption is questionable at best, and can cement crude racial stereotypes at worst.
But today, many people no longer consider a colorblind society a worthy goal. Aspiring to colorblindness is racist, they tell us, as it uses the guise of neutrality to reinforce the white supremacy that underpins our institutions. Instead, we need to go in the opposite direction by instilling in everyone a strong awareness of their racial identity and associated cultural heritage, and by explicitly considering race in hiring and admissions.