Here is Mike Colter as Spartan Locke in Halo 5. This is his campaign asset. This probably took 343 hundreds of hours and thousands of dollars to do. They can make his skin slightly lighter, give him an afro, braids, a goatee, a full beard. But they can't make him look any different than this.
That same issue happens in Black Ops 3. They're got two motion capture actors for the campaign. And they've tried to vary them up, different beards, hair coolor, tanned skin, paler skin. But they can't essentially do blackface, nor can they make them look Asian or whatnot. The multi-player has several different ethnicities, Asian, black etc. Just crazy, even when games are super progressive, and have men and gender lead campaign players, several people of colour as supporting characters, several different ethnicities and races in multi-player, it's just not enough.