Because its still within living memory of people we know and interact with on a daily basis.
Bet you any money go to china they'd have the reverse opinion we do about nazi's versus japanese. (Interestingly the japanese are still kinda bitter about getting nuked, and see the kamikaze pilots as heroes, despite one statistic i heard if the war had ended ~14 days later than it did both nuclear blast deathtolls would have been paid for in chinese blood, then japanese blood as a land invasion of japan would have pitched bittered gi's with flamethrowers and machine guns against men women and children with anything they could find)
I tend to feel sorry for the germans, carrying around this stigma in europe even to this day, i'm firmly of the opinion that the nazi train only got traction because of what the "good guys" (ie us supposedly) imposed on the german people after ww1.
when your starving and having to run from work to the shop with a wheelbarrowful of money to buy bread before the price rises beyond what you can afford, then suddenly a man comes along with clear ideas, a plan, i'll make america germany great again, its those damn muslims mexicans jews swanning around with all their cash, immagrants stealing our jobs.
And suddenly there are works programs, employment, a new currency and you can actually afford to buy things, sure the fuhrers ideals might be a little off but my stamp book for a new volkswagen is half full and i heard the secret police took johan down the street away for being a revolutionary.
The next thing you know theres a war on, they want to kill us all, we must fight to protect our land but we're great now, they stomped us last time but we starved for it they deserve everything they get, and we could win this, EIN REICH, EIN VOLK, EIN FUHRER!
The best thing america ever did was pour money into rebuilding europe, and especially germany, after the war, sure they mainly did it as anti communist propaganda but look at germany now, doubt we'll see the like from them again.