There is nothing wrong with questioning the conduct of the war, with an eye toward improving it, but doing it in public serves only to embolden the enemy.
FDR made serious mistakes in the conduct of WWII, but they were not brought up publicly, during the war.
One mistake FDR didn’t make was taking only a small fraction of the country to war. Had GWB done as FDR did, we might have a different homefront.