As much as I don't agree with changing skin color to appease the masses, unlike the new star wars movies I didn't get any social warrior vibes from this show at all.
I've not read the books or played the games (though I do have witcher 2 on my 360 but never got around to playing it and I tried to buy witcher 3 two days ago but because of the show it's sold out everywhere I went) and I believe that most of the people who are watching the show are in the same boat.
Changing a few characters skin color, as long as it doesn't negatively affect the source material, in order to make the show more accessible for a wider range of viewers isn't a huge issue for me.