It wasn't Eisenhower's decision to make any more than it was MacArthur's or Nimitz' in the Pacific. The smart thing the US did was the Marshall Plan in Europe and Japan. That pretty much ensured that Germany and Japan would not have a grudge to bear from defeat, unlike Eastern Europe that learned to hate the USSR with a passion.
Agreed it wasn't his decision; it was Truman's, but certainly he had input. The logic of helping them rebuild is the same we should have done with Afghanistan after the Soviets were defeated.
It's not nation building to help others rebuild since they become trading partners.