Ethnic diversity has seemed like an odd point to me since my time in the military. See, when someone in the US talks about diversity, what they they actually mean is (usually) how brown someone is. Regardless of ethnicity, though, people living in an area are going to deal with the same terrible traffic on that one major road, cheer for the same local sports teams, talk about the same local politician who got caught doing something embarrassing, and chat about the same unseasonal weather. I worked with a group of people who were diverse in a different way. We had people from all corners of the country (literally: an Airman from Anchorage, Alaska and another from El Paso, Texas), a guy who grew up on the US base in Germany, another from Guam, and these two guys who had, respectively, been a prison guard and a convict. I enlisted just before Don't Ask Don't Tell was repealed, but we had a few people in the squadron who were pretty obviously gay, and none of us cared as long as they got their work done. On the other hand, we also had the backwoods country boy who had never met a gay person before and was more than a little uncomfortable with the rampant homoerotic military humor. There was ethnic diversity (though it seemed like most of the squadron was at least a little Irish), but it never seemed like a thing. My wingman was never "that Irish/Mexican/Native American/Asian guy," he was "that dude from Seattle." Really, my wingman was 1/4 Irish, 1/4 Mexican, 1/4 Chinese, and 1/4 Chahalis tribe.
I don't really know what my point is, thanks to sleep-deprivation madness, but I think it might be that diversity means different things depending on who uses the word.