The problems with SotS:
1. Yes, the book that movie was based on takes place in post-Civil War Reconstruction. But, two problems with that...
a. The movie never makes that clear, so, it can be easily interpreted the African workers are still slaves.
b. The time of Reconstruction was not a happy time for the freed slaves. Jim Crow laws kept them segregated, disenfranchised, and poor. And this leads to...
2. The problem with the movie's portrayal of Reconstruction freed African Slaves and Walt:
a. The movie shows happy-go-lucky African workers. None are in positions of power or prestige or respect, except for the literary genre of the "Magical Negro" whose identity has worth because of what sort of special wisdom/power/ability they have to help the White protagonist.
b. Walt, to his credit, did seek out advice from Black leaders and they told him to cut the happy, singing portrayal of freed slaves as if they weren't still suffering the after effects of slavery and continued oppression. Walt, to his discredit, ignored their advice and that's why the movie remains in the vault. Walt suffered from the casual social racism of his times, which would diminish his culpability if it wasn't for the fact that he intentionally disregarded the advice of Black leaders. Let's not forget all the other racial stereotypes in all the other Disney products... which again, common during his time -- Bugs Bunny did the same.
3 Besides the historically whitewashed portrayal of the freed African slaves (without making it clear they're freed), there is the awful stereotypes of Southerners... think "Hillbillies." The slow-talking drawl and distorted features meant to indicate inbreeding were meant to highlight the characters' stunted mental development and lack of education. Maybe Disney can spin the movie today to say it was subversive: It showed the Africans as happy and normal, but the Southerners as inbred hicks.
4. The stories Uncle Remus tells have their origin in African folklore. But they were appropriated into a U.S. Southern framework. A reboot of the movies would be to retell the stories using the CGI animals seen in the live action Lion King remake (not the same Lion King characters). You can still use Zippity Do Dah.