And even those images cannot communicate what it was truly like.
I saw the shot of the tank with dead marines piled on top. I don't think that was ever released.
I think the military knows that it cannot allow the populace to get a hint of the hell of war because some conflicts are lost when the people at home loose the will to support the war. Their argument is that the enemy controls what the people see on the other side, so we are just countering their advantage. 
So as you say, if one is going to choose to fight a war, the cost should be fully understood. However, if that had happened, North Vietnam would have taken over the south earlier, and the dominoes would fall until all of Asia would have been Communist. At least that was the propaganda.
What lies are we being told today?