I've recently read the memories of Sebastian Haffner about his experience of 'coming of age' in 1920s/1930s Germany, and at one point he mentions that the Republic basically had one politician who had a real popular appeal and the potential to make politics interesting for the younger generation: Walther Rathenau. He even describes him as one of the five or six personalities of the century, and that it was the very contrariness he embodied (being an "aristocratic revolutionary, idealistic economy organiser, Jewish-German patriot") that made him appealing to the masses. Therefore he could have been a good candidate for a 'democratic populist'. Stresemann certainly stood for stability, but he didn't have that same appeal.