My guess is: More is coming there. They did use actual face scans as basis for the character faces, and I doubt all of them are implemented yet, since the selection is rather limited in general right now.

That being said: Again - like in many other games apparently lacking "representation" - you also have to keep the setting in mind. In the Realm's northern/middle Swordcoast, European/Nordic and Arabic/Indian ethnic equivalents are the vast majority of the population, while Asian (Shou-Lung, Kara Tur) and black African (Zakhara) analogues basically are non existing, since their respective countries are far, far away and their people usually don't venture far from home... aside from the odd, wandering Shou monk or southern trader/mercenary, maybe.