In many ways Thurmond represented a continuation of Wilson and FDR. Strange as it may seem now, Thurmond, while definitely a segregationist, was regarded as a liberal when he first entered politics.
The New Deal generation of American historians wanted to see US history as a simple story of good and evil.I disagree. The New Deal historians did everything they could to cover up the evil of their heroes, and everything they could to uncover the evil of their enemies. Moral ambivalence was nothing of their methods. Moral obfuscation was the game. The white washing of Wilson's racism is a good start. Then we can add T. Roosevelt's extreme -- if not racism -- racial politics. Roosevelt upheld the black as a means, little more.
Above all, the New Deal historians were embittered by hatred for Harding. Harding, that blithering, blathering fool, that idiot, that corrupt ass... kicked Wilsonian democracy in the crotch. Harding killed Wilson. New Deal historians never forgave him this. Whenever they look back at the 1920s, the 1910s, the 1900s, even the 1890s (as seen in their treatment of McKinley, that nice, listless man), they framed it by Harding. To them, if a Republican led somehow to Harding, he was scum.
No, they weren't interested in good and evil. They were interested in good alone. Evil was for their enemies.