I suspect Jonah gets this right: Asian-Americans would not only be more numerous overall, they would be disproportionately in STEM, and disproportionately not in various ethnic and gender studies, nor in the social sciences. I will bet this applies at the affirmative-action end of the scale as well. Black and Hispanic students are likely over-represented in those studies. Females are under-represented in STEM. I would be only guessing where they are over-represented, yet I'll bet I'd guess pretty well.
It would put the squeeze on legacy-influenced admissions as well.
If the barriers to Asian-Americans were removed, the next year there would be fewer students in those courses. In four years many of those courses would be gone, unsustainable. This would affect not only the number of professors in departments, but their relative prestige. That would be unacceptable to them, individually and collectively. Their loss of status would be taken as evidence of sexism and racism.