Hitler is a symbol, not a person - it's a socio-historical issue, not political but more philosophical.
You rarely see him in games since many allow you to choose sides, and thus having one side be represented by Hitler might raise a lot of eyebrows, or more.
Germans go all nuts when somebody brings him up, as was already mentioned. The older generation gets all worked up and thus bans everything showing swastika in newer media, or lets it get removed. No swastika on Buddhist statues in comics, in medieval Japan in manga, or on people you can only kill in video games.
Think about it, the youth might identify with that! Better not show it to them! Confrontation with it is only to be made through several months in school and highly artistic and pretentious movies!
Other countries and their mentalities might be less sensitive about it, but it works along the same line. No symbols of the Nazi regime to identify with, period.
Oh you gotta be getting me...Hitler harnessing the power of the Spear of Destiny and a lovecraftinan horror? who wrote that game's plot?
Actually it's not Hitler. Anything else I could say would be too spoiler-ific.
I am 99.99% positive that there is no swastika in any official release by Paradox. It is incredibly easy to mod into the game though so screenshots and videos with that flag are very common.
That is correct, the swastika is not present in any official version of their WW2 era series.