being german, with jewish ancestors, i can say that the black-and-white depiction of "your average german nazi" is just a few REALLY bad people who drag down the rest with them. Of course, it wouldn't have come that far if more people had woken up, but still, i find the idea of playing a nazi interesting, if made with very cautiously, cause there's just a fine line to walk on, and we all know how the media can make the biggest controversy out of the smallest mistakes.
So, playing a nazi character is difficult because of so many ethical pitfalls, but if you mean "german soldier in WW2" then i guess that could be developed into a nice story... god knows how many diaries of fallen german soldiers are around.