Not sure how playing as a black avatar would be different from playing as a white avatar. Does the black avatar have powers the white avatar doesn't? Sounds a bit racist just to say that it would be meaningful to do this if one point of the article was that you don't even have to use it to educate.
Unless the game somehow educates us on the minority's culture or how other culture's interact with them. Otherwise it would be entirely pointless with no intrinsic difference besides looks. Really, except for in cutscenes I don't even really notice avatars while I'm playing the game anymore than I notice my hands while I'm driving. Avatars are just tools, extensions of oneself that allows interaction within a digital world. As such, I can be a little red rectangle and not bat an eye. So why would being a differently-toned skin color make any impact by itself?
Honest answer, I get that people have to deal with prejudice. I get that people withhold jobs and common niceties based on race, gender, religion, and orientation. I've been held back based on race and gender too and I understand how that feels. Even if I hadn't been I'd have understood the feeling. I honestly do not desire to be dragged into a lesson that many of us already know just because someone thinks I'm ignorant because I'm white, male, or straight. It's the same reason I hate the anti-cigarette ads even though I don't smoke. Yeah, I get it, smoking is bad but you're grossing me out with absolutely no justification to be talking to me, a non-smoker, about quiting. Hell, I want to start smoking just to ease myself after some of those tooth pulling/skin tearing ads.
Then again, maybe this would make a difference for people who focus on race. I mean, you wrote the article in a way that you actually wondered if a character was disagreeing with you because they were a different race. You were literally having racist thoughts about people just because they disagreed with you. How you played the same game I did and focused on race the whole time is interesting. But here's a question, when you play a game as a white character and are in a disagreement with a black character, are you wondering if they're just arguing with you because you're white? To me, they're just 1's and 0's so the thought of them having been raised with prejudices doesn't occur to me, but this is highly fascinating to think of people who do attribute history and other personifications to a digital creation.
I think what you really mean is that ignorant people should put themselves in other people's shoes. That's a good statement. Instead you made it racist, sexist, and whatever you'd call someone who thinks a person doesn't understand something based on orientation. It's a pretty lofty statement to think we would all benefit from that. But, from the words on your article I see your own personal experience was enlightening for you so perhaps you just assumed that it would be meaningful for others too if you weren't racist and it still made you think.