@Tinuviel I think you're conflating a few things. One, having a fantasy setting decide to basically forego racism as part of the theme doesn't mean that all the players and the OOC experience will suddenly be free of bias, because OOCly we're all still brought up in this system.
Second, I think you're conflating "this experience was valuable for my personal learning and I think others could find it valuable, too" with "all games must provide this specific experience in the same way." I mean, I already don't think that the MMO examples are going to apply the same way to MU*s for all of the reasons that have been mentioned on this thread already. (The visual/graphics component being the most relevant.) But it does remind me of the instances I've heard of where a male player has decided to play a female PC and experienced, for the first time, how the OOC tone becomes different. And how that helped them better appreciate and empathize when female players would be frustrated at being targeted and harassed by creepers.
I felt like the overall message was just, as I said, "I found this illuminating in regards to better understanding some small piece of the difficulties those different from me face." Honestly, I don't think you have to play out IC stories of oppression to experience some benefit of broadened horizons. A lot of the time, deconstruction of these internal biases start with just experiencing more stories with diverse characters at all. It helps to break down our default assumptions.
A setting wherein racism and sexism don't exist may not be educational on the ways in which these forces work in the real world, but they do provide a place to explore characters as equitable players in a common story, and that in and of itself is valuable.