There was a coup in the Japanese military to try to prevent a surrender after the nukes were dropped. Things are far from that simple.

Now, one thing I'll agree with is that Japan would have surrendered long before on the condition that the Emperor would be kept in place. Then we got the unconditional surrender, and after all the peace talks were done and documents signed, we still allowed the Emperor to keep his place. The argument here is that the American people were out for blood and public perception would only accept unconditional surrender. I don't think that's a very good moral argument, though, especially when it led to nukes being used in anger.