Well this is a tough one. For pros there weren't really any besides the end of the war, but even with that the Japanese kept fighting of long time. Hiroo Onoda is example of this. It also costed the Japanese many funds and killed many innocents.
Without it though, it's possible that Japan would never be on good terms with the US and never been brought to Justice for their warcrimes under Hideki Tojo (Japanese minister if war)
