I've often considered the possibility as well, of trying to do a game from the perspective of a German soldier. The narrative would be incredibly important. But, I've also always felt that the game would be worthwhile. Having a game that allowed you to be portrayed as the ultimate hero, but eventually revealed to you the how horrible your cause was (a la Deux Ex, par example), and maybe gave you the opportunity to turn against your side at some point (July 20th plot, [a href=http://en.wikipedia.org/wiki/German_Resistance]German Resistance[/a]) would be an incredible emotional ride. I've always wanted a game to make me think I was the hero, and allow me to fight and slaughter the opposition, then turn the tables on me and reveal that everything I had done was pure evil. Haze is going this direction, and I hope to have the opportunity to play it someday, if it turns out well. From a historical perspective, a game allowing you to play as a German soldier would perform a similar function.
Not to mention, despite their losses later in the war, much of the early war was nothing but success for Germany. You could spend quite a bit of time winning, before changing allegiance around the same time Germany starts losing.
As a side note, I don't think any publisher would ever make this game. Too many people would decry it as a pro-Nazi thing, without ever looking beyond the wrapper. As an alternative, I think a game with a fictional setting could heavily parallel the situation, and get much of the same effect, preferably heavily hinting at it's source material.
But, you never know. Eastwood managed to make the Japanese seem human in Letters From Iwo Jima, maybe someone could portray the Germans similarly? The movie [a href=http://www.imdb.com/title/tt0102443/]A Midnight Clear[/a] from back in the day didn't do a half bad job, from the American perspective, but I think we can get more looking from the inside out.