I think a lot of people have missed the point. There is still a number of Nazi groups operating in Germany. Nazis, almost by definition are not very bright - their messed up beliefs are clear indication of that.
The German legislation about not having Nazi imagery in the media is presumably so these groups (and anyone stupid enough to be thinking about joining them) have nothing to latch onto, no matter how vilifying towards the Nazis. You can easily imagine someone with that small a brain capacity seeing a swastika in a game or a German stormtrooper saying "Cool, Nazis! Nazis are great, there's obviously lots of Nazis about - I'm heavily influenced by the herding instinct, I'm going to get up to Nazi things". It's a sad fact that the more people are aware of these extreme right-wing groups, the larger they get.
It's not a factor of censorship or liberalism, it seems that the German government don't want to see the same mistakes being made again.