Brilliant observation: mine too, as my dad was a sailor aboard the USS New Jersey, which would have without a doubt played a role in an invasion of Japan proper.
Although Truman's later bungling of the Korean War and firing of Gen. MacArthur left a black mark on his overall record, he showed immense courage in making the decisions regarding Hiroshima and Nagasaki. In that respect, HST was a statesman: an unfortunately vanishing breed in politics today.
Truman was one of the very VERY few great democrat presidents.