Controversial opinion, but racism and expectations are probably the reason behind the holocaust receiving so much attention. The Western world has a powerful influence on history and how things are perceived, so we often see the world through that lens. Germany was a civilised and highly developed, White, Western County. So when this happened, people were more shocked because it was committed by a nation with their own "kind", which is why they expected better. In contrast, attrocities in Asia or Africa arent as well known, because the Western World doesnt really expect better from these people. Racism is deeply embedded into the Western world view, which is why we have such a skewed view of history.
Note: This post doesnt reflect my personal views, I am just commenting on how things are perceived.