I don't find it surprising that Disney isn't releasing SotS on DVD, as it's incendiary still, though I also think easily accessible films like Gone With the Wind give an equally antiquated portrayal of African Americans. I agree with previous posts that with proper historical contextualization through audio commentaries or extra content, an educated viewing of the film can be had.
Still, I'm not holding my breath. Disney is less concerned about history than it is about mythology. Indeed, SotS had good intentions in portraying African Americans as a mythologized simple, kindly folk (its a condescending stereotype, but, hey, its positive--I mean, its not Birth of a Nation), but that mythology has, thankfully, changed. It's not a bad thing that today African Americans have more control over how they're portrayed in the mainstream media. SotS is a great example of white people trying to tell black people who they are. Not cool. (It's the same pitfall Disney fell into making Pocahontas--good intentions ending up as condescension.) That doesn't mean that SotS should be completely taken out of the discussion of race in America.
Having seen SotS on a video released in Japan about twelve years ago, I do think it is disingenuous of Disney to be willing to have other nations get an inaccurate perception of African Americans, but not having the guts to risk an uncomfortable discussion in its home country of America.