Ummm, I think you need to read a history book... I suppose you couldn't pick one up without seeing Hitler mentioned as a keystone in 20th century history... as for Napoleon, he caused the death of untold hundreds of thousands of people in Europe, brought France to ruin, and was himself one of the biggest losers in history...
If by being a big fat loser, you get to be in Civ4, I see no reason why Hitler wouldn't be in the same category... like Napoleon, he caused the deaths of countless people and brought ruin to his country.
You don't have to win wars, build autobahns or open schools to be important to history... you just have to impact history significantly to be remembered and important... certainly Hitler did just that... if he didn't why would this same exact thread come-up over, and over, and over, and over, and over, and over again?!?!?
I'll bet the History Channel does more on Hitler then Napoleon in any given week by a landslide too.
Finally "Churchill 25", you need to actually READ what I'm replying to... the quote: "Why would they put in a leader whose legacy for his country was near-total destruction and unconditional surrender?" is what I responded to... did Napoleon, Montezuma and Hannibal not cause near-total destruction and unconditional surrender? Check a history book or two (just remember to pretend the Hitler section isn't in there... he's not important, remember?).