It depends what the goal of defeating Japan was. If it was the reason the US and British gave for cutting off their oil supplies before Pearl Harbor, i.e. end Japanese imperialism in Asia, that was already accomplished by forcing them back to their own island. If the goal was (for the first time in American history) unconditional surrender of an enemy, well unprecedented demands cause unprecedented resistance which could only be overcome with an unprecedented response.
An excellent examination of this topic (available from JSTOR):
Hiroshima and the Historians: History as Relative Truth, KENNETH B. PYLE, The Pacific Northwest Quarterly , Summer 2013, Vol. 104, No. 3 (Summer 2013), pp. 123-132
In hindsight, the fight between Japan and China was over who would control Asia.
Knowing what we know now, I would have much rather had the Japanese in charge than Communist China. China is doing their own version of the “Greater East Asia Co-Prosperity Sphere”.