But there's another thing here, besides the arguments about predictive power and fairness: As noted in the comments, a selective college is a place where the kids who always did really well in high school can suddenly find themselves in classes that are actually hard, and with classmates who are smarter than them. UCLA and Berkeley currently function as those sorts of places. There's some value in that. If you open up UCLA and Berkeley to a wider cross-section of 18 year-olds, you might achieve certain types of fairness goals, but you'll also have to teach the classes at a level where a wider cross-section of students can succeed. Yes, yes, some of the new additions will outperform expectations, and for those who out-perform you won't need to lower the level of anything. But the definition of a statistical expectation is that those who out-perform will be balanced by those who under-perform, and you'll have to choose between either failing them or accommodating them.
If the only conversation is a normative one about whether to fail or accommodate the students who aren't at the top, well, I guess the question answers itself. But if you expand the conversation, you'll note that we still have these top academic achievers in the classroom. If you don't accommodate them they will be in the same spot that they were in during high school. They will remain the smartest kids in the room, and that will have its own effects going forward. Even from a 100% anti-intellectual standpoint, wouldn't you want those kids taken down a notch? That won't happen when the classes are being taught in such a way as to ensure the success of their less-accomplished classmates. Similarly, kids who might have been closer to the top in a less selective school will be only middling at UCLA or Berkeley. There's no real need to weep over that, but please ponder the implications of a world where nobody's self-perceptions change after high school.