But there are 2 important points to consider: 1) The allies did not care about the Nazi genocide until after the war had begun in earnest. In the US, whatever anti-anti-semitism Roosevelt felt, it was clearly less important to him than losing the anti-semite vote by stridently coming out in opposition to the Holocaust already in motion (or even permitting the refugees from the Holocaust to come to the US). Stopping the Holocaust or the Japanese crimes against humanity was, for the most part, a consequence of accomplishing their other strategic goals, not a strategic goal unto itself.
2) The terms of the treaty of Versailles was unambiguously a major cause of Hitler's rise to power and the start of WW2. England's and (especially) France's desire to punish Germany led to a lot of terms that punished the people of Germany, but largely left the decision-makers relatively unscathed.