250,000 Marine and 850,000 US Army soldier would have disagree with the OP.
As usual, this topic are derailed by trying to debate an historical event while benefitted by Hind Sight. Of course it would be easy for all of us sitting in front of a computer and side seat drive what the US should have done in the 1945.
Rule 1 : Never discuss an historical event when you consider what you know today.
What if you are one of the Infantrymen who just come from 2 months fighting in Iwo Jima and 4 months campaign in Okinawa? At that point, you only know this, you survive a mad fight in Iwo Jima, where 1 in 5 of your buddies dies and 1 in 2 of other of your buddies are wounded. And you are facing an enemy that literally fight to the last man (If I remember correctly only 216 of some 20,000 garrison surrendered) and then done that, and you move on to the next war in Okinawa. Which is simply 4 times bigger and 4 times as cruel as the one you just fought to finish 15 days ago. Only this war, 1 in 4 of your buddy never made it home and 1 in 2 are casualty.
Now they are telling you that you are going to Tokyo or some magical bomb that would destroy a City in 5 second. Now tell me, if you are an infantryman in frontline, which one do you prefer?
Rule 2 : There are no "READY TO SURRENDER" there are only surrendered or fights on.
War don't stop just because of you want to make peace, there are only 2 states in war, that's WAR and PEACE. trying to get there, wanting to get there,, willing to get there mean absolutely nothing in War. Or you really believe "Since we are talking bout peace, maybe we should cut down fighting?"
I am sorry, war does not go that way. In fact, if History are any stand point on this issue. Most war had actually seen more casualty during peace talk. 2/3 of Casualty during Korean war are during the peace talk stage, it does not help when the war drag on for 2 more years (2/3 of the whole war) in peace talk.
In Vietnam, 3/5 of casualty appear during and after Paris peace talk, that happened from 1969 to 1973
Rule 3 : No mercy or quarter given in war.
Have heard enough of "is it enough to just shot his hand, leg or anything but not kill him?"
There is a reason why Special Force were taught to double tap. Where you bring down your enemy with 2 shot in the chest and come up to him and shot him once in the head just to make sure.
In War, there are no maybe. And each time you second guess your decision from the "maybe" would simply kill more of your own men. You can sit in the corner and think about what "Maybe" or "Could be" when the battle or war is all over. You have plenty of time to think about that, trust me, 10 years after I came back from my first battle, I still think about the decision I made during my war, and what could be of different. But when the war is still in progress, there are no maybe or could be. Maybe they want to surrender? But what if you are wrong? Do you want to bet your life or god forbid, your friend's life on it?
You may not agree with me, but again, this is how I see things, war is just like that, it would be naïve to think otherwise.