Wouldn't a monoculture of yes-men, for example, be less likely to kill a failing project early on, and save money that would otherwise be wasted? Having a diverse team will provide better input on business practices, processes and work ethics, which all impact the product a business produces, and ultimately their bottom line.
I am not sure culture counts matter as long as it is a good culture. Sure a mediocre multiculture is better than a bad monoculture but that just means mediocre is better than bad not multi better than mono.
This said, if you are running a mining company, an automotive giant, or you are operating in any industry where the priority is on reliability and tradition, I can understand why diversity could make you nervous. But never forget that diversity can become a way of life.
That's very much what hapenned to American culture anyways with the great melting pot, isn't it?
Uh, that would appear to be you.
Actually, you can do the same right here at home by hiring minorities