eh all evil military stuff in movies is shown the same way. I just don't overthink it.
Yeah. Since movies are still relatively young (as I recall, first world war was shown back home in black/white and no sound with old picture reels) they seem to have this evil military is similar to Nazis formula. Since movies probably spread proper around WWII (cartoons with Donald the Duck fighting/being/whatever Nazi, even...) it does make some amount of sense, too.
Jeremy Irons voiced Scar and if his side is meant to be an allegory for Nazis (it isn't), then it's a pisspoor one since the hyenas are more ethnically diverse than the lions.
Then again, I never heard Rickman too much, either. I saw the HP movies the most in Czech, and would likely be able to tell the voice actor there better than the actual actors.
But yeah. Ethnical diversity makes little sense for Nazis, with their Aryan race bullshit. (Scientifically proven to be bullshit, too. Yay for science!)