I think that historical importance of Soviet roll in that was was purposely minimized to morally excuse nuclear bombing of civilian targets and to lessen the sentiments towards the people of soviet union who played the key roll in fighting Germany. This is very important to keep the general population afraid of commies.
Even today people reject well researched stuff like this out of hand within minutes of being confronted with it.
WWII was a complicated affair, no part of it (beginning, middle, ending) will benefit from a simplistic view.
For each of the parties there is a different viewpoint, and some of those viewpoints have been repeated so often and so loud that for many people to consider that there might have been an alternative is hard if not impossible to accept.
I always found the bleating moral outrage over the nuclear attack more than a little grating and ignorant. As horrific as Hiroshima and Nagasaki were, the fates of Tokyo and other cities were little better.
The B-29s dropped white phosphorous, napalm, avgas, etc in specific patterns intended to create a firestorm -- a phenomenon pioneered by the British in places like Hamburg and Dresden. The flames were so intense that subsequent waves of bombers were lifted in flight, and the glow could be seen for hundreds of miles. Over 100k are estimated to have died. A million+ were homeless.
This isn't something that was covered up/deempathized, nor was the atomic bombing. Obliteration of the enemy from the air was heralded during and after the war.
It was far more effective against Japan, especially because they used wood and paper as building materials. The crews of the bombers at the tail end of those bombing runs could even smell the stench of burning human flesh.
Far from covering it up, this kind of thing was a massive boost to the career of Curtis LeMay, the man later charged with commanding the Air Force's nuclear arsenal as commander of SAC.