black women and other women of color are being constantly blasted by images in the media and by social pressure suggesting that having hair like a white person's is better than whatever they have naturally. In other words, it is really not cool.
And this is very relevant to comics today. See also: the controversy over Misty Knight and Monet St. Croix being whitewashed in their respective books, or the debates about Storm's hair that have been going on for decades. (I seriously cannot think of a time that anyone has looked at Ororo's hair and mistaken her for someone old or ill--but I can think of examples where people like Kitty have marveled over how "extraordinarily beautiful" or "unique" her light hair makes her.)
Fletcher Hanks died an unknown (even Will Eisner could barely remember him) and there appears to be no surviving documents or interviews that shed light into his creations. (The mystery is possibly one of the things that make bizarre characters like Stardust appealing.) There is no way to know if he spouted hate speech daily or if he genuinely thought he was being progressive in his depiction of African people. So for all this talk about whether he was "well-intentioned or not"...we'll never know. The work has to speak for itself. Depictions of yellow peril villains named "Slant-Eyes" and good but childlike, nameless, and voiceless Africans who need a powerful white protector--are racist. And come on, of course you can be artistically bold and daring without being potentially racist.