I think the idea is that an artificial means of creating a diverse workforce will allow people in traditionally disadvantaged populations earn decent salaries so that they can live in decent neighborhoods, and therefore send their kids to decent schools, then to decent colleges, then to decent jobs, where they can have kids and send them to decent schools ... eventually leading to the point to where that population does not need artificial means of creating a diverse workforce anymore.

Having grown up in an incredibly heterogeneous global environment, I personally believe diversity is good to have just because it helps break down the innate (my opinion) desire to stick to ones own group/type, which is often the source of much conflict in the world. I can't back that up with facts, just my opinion. I genuinely feel that I am a kinder/more productive/more flexible human being for having grown up in a very diverse environment. It's hard for me to explain why I think diversity just for the sake of diversity is absolutely a positive thing. At some point I'll have to hash it out and do some research.