Lenin the Moralist
It will probably cause me to lose friends all across the political spectrum when I say that the problem with Lenin was that he was too moral, but that is indeed my position. Perhaps the chief innovation that Karl Marx brought to the socialist and communist movements was that Marx presented a non-moral critique of the capitalist system. By this, I do not mean to imply that Marx was personally either immoral or amoral, but simply that his economic theory was not an argument based in morality - just as a chemist, when analyzing a chemical compound, does not present moralistic reasons why a molecule should be composed of such-and-such elements. There had been many socialists and communists before Marx came along, and there had been many economists who analyzed the capitalist system, often in quite critical ways, pointing out, for instance, the massive inequalities between classes that capitalism produced: see, for example, William Thompson, John Bray, John Francis Bray,...