This makes for a more interesting story and lore; it gets people thinking: "Whoa cool, another nation with different people, I wonder what they're all about!"
Whereas in this show, and many like it (Wheel of Time), all nations have been forced together to form a single uninteresting soup where few have any cultural significance or quirks whatsoever, so as to avoid offending anyone with stereotypes, which could lead to (GASP!) mild and harmless racial jesting, stupidly redefined as violence against an oppressed minority group by vocal activists who live and breathe dismantling Western/European culture.
We can easily add in lore friendly blacks and do it in a way that makes less spoken about factions more interesting.
Why do low effort tokenism when you can do something interesting and still diverse?
All it takes is a bit of effort.
They're doing something cool by having the diverse cast, but the writing doesn't adjust to make a story that feels like it has a diverse cast