Depends what you mean by diversity. I think diversity of thought and opinion is important in everyday life, and in business. I discussed this here: Moral Equivalents? - #94 by Drew1411, but during some MBA courses the business case for diversity was brought up. Research shows that diverse teams have better financial returns and more innovation.
Depends on how close your margins are. I think you can get away with group-think for a while, but eventually it can bite you in the ass.
Non-diverse groups can miss out on opportunities from others they are excluding from their group due to their club/tribal nature (i.e. if you don’t hire women or make women feel included int he workforce, you would be missing out on any potentially talented females).
I think the way we measure diversity today is flawed, but is the only meaningful way we can measure it. Just because somebody is a certain gender/race does not demonstrate their thought process, problem solving skills, social awareness…etc. There are quite a few different personality tests out there that I think provide a more accurate picture of how that individual will contribute to a group.
I think there are diminishing returns to diversity (again, diversity of thought) as it can slow the process down. At a certain point you need to move forward and not discuss ideas and challenge things anymore, and less diverse groups will be able to agree quicker and easier. The research I mentioned above mentioned this specifically, but said that even though projects took more time up front they had less issues down the road.
I think this is more along the lines of diversity of race/gender…etc. I do not think legislating diversity in the sense of forcing companies to have specific percentages of populations or genders is the right thing to do, as I mentioned above, diverse businesses have incentives to diversify and the ones that do will receive those results. There are also the social incentives of being a diverse company that are beneficial.
I think the case of legislating diversity can be made for reparations for previous wrong doing, but that conversation has been had many times in different forms here. Not sure if we need to re-hash it.