The US ruthlessly destroyed the Japanese navy just as the British did to the Kreigsmarine long after it was a threat. To me this was more to stop ships falling into Russian hands at any subsequent peace deal.
IMHO this is because the USN was attempting to obtain Naval supremacy - not merely control. Remember, the US was planning an invasion of the Japanese home islands. Any IJN ships that were seaworthy would do what they could to break up or disrupt an invasion. Even a couple of destroyers in the wrong place at the wrong time could do a lot of damage before they were sunk, and the Japanese had already shown plenty of willingness to commit to suicide missions.