The hard truth is if you only hire white guys from Stanford you've got a ton of overlap in their background and the way they think. If you only hire black women from Somalia it's the same. You're going to have significant similarities. Making teams more diverse is extremely important and beneficial as long as all are otherwise qualified.
Designers, sure, it's very eqsy to think of examples where diverse backgrounds improve business outcomes. But let's not pretend that there is any difference in business outcomes if Foxconn's assembly lines snapping iPhone parts together are entirely Chinese hands vs if they were to equally represent all members of the united nations.
Asserting that there is a benefit needs to be seriously qualified, as it can certainly be everything ranging from a benefit, to negligible, to an actual handicap.
Although at the same time and despite being pretty far right on the political spectrum, I think there is some truth to the idea that big companies "should" hire visible minorities over and above those that are fully qualified, but it shouldn't be done at the expense of legitimately qualified people, or that it causes significant harm to product quality.