While Hitler had many great qualities and ideas, he also had many bad ones. It's the concept that great men also have great flaws. Hitler was prone to prejudices and grudges (many great men are) and seems to have placed too much trust in members of his inner circle. I attribute many of his poor military decisions late in the war to the quack of a doctor who was treating him with "holistic cures" and "state-of-the-art medicine" but was in fact simply pumping him full of narcotics. Hitler being a trusting man could not see that he was being scammed and poisoned by this doctor even when confronted with evidence by the Chief Surgeon of the NSDAP and Army. https://en.wikipedia.org/wiki/Theodor_Morell

Also, as comfy as NatSoc ideology is, I still find its totalitarian bent and suspicion of Christianity unappealing. Also, it seems that it's really just monarchy with more steps, so I don't see what is gained over a traditional monarchy.