as for the celebrated ones...most likely because their positive contributions far outweigh their negative views/actions... and time has a habit of stripping away the bad stuff.
taking time into context, there's no way you can argue that a white person who supports owning slaves would be widely accepted in the 1960's... they too would be controversial.
Malcolm X also preached that white people were the devil.... do you also agree with him on that point?.... do you agree with him on the points of black supremacy? how about his view supporting black and white segregation?
do you also find yourself supportive of every black supremacist group in existence that carries on his teachings?... or do you blame the evil white people for their views as well?