Psyringe: With regard to "Nazi symbolism" - while most people seem to think that this is some strange German idea of censorship, it was actually the allies (US, UK, France) who banned Nazi symbols in the defeated German provinces.
Export: Are you sure about that? I can't find any reference to that,
I actually spent quite a bit of time researching that matter (triggered by a discussion why Hitler doesn't appear in Civilization IV). I think I took my statement from above from official educational material issued by the German Parliament, which ought to be a pretty reliable source. I'm not saying it's indisputable (and arguably a scientific exploration of the origins of this law might be a better source, but if one exists, then it's collecting dust in some university's library, and is out of reach for me). In any case, I'd rate my source as more reliable than google searches. ;)
Export: and while it would obviously make sense that the Allies would want traces of Hitler's dictatorship and ideology removed, it doesn't make sense for them to force a law that would also cover its use in games and films and so on - and then for Germany to keep it for over 60 years.
The allies weren't concerned with any exceptions for entertainment material, they simply banned the symbols period.
When the Federal Republic of Germany was formed, the German legislation had to decide how to deal with that. The current law at this time was that the symbols were banned. The German legislation _could_ have changed that, but can you imagine the international outrage that this would have caused? Nazi Germany, the scourge of the world for about a decade, responsible for countless abominable crimes, gets its independence granted back, and the first thing they do is allowing their people to display Swastikas and Hitler Portraits again?
And while the international community probably wouldn't care that much if the Germans lifted the ban now (or 20 years ago), it would now be the wrong signal internally. There are groups of neo-nazis in Germany who would immediately see and present this as a nation-wide approval of their politics.
Whether or not any German legislation ever _wanted_ to lift the ban is an interesting question, however, it's not all that relevant. Because after the law had been enacted, it had become impossible for Germany to lift the ban, for the reasons mentioned above.
If you're interested in the details, I can look whether I can find my notes from back then, but it's been a few years ... on the other hand, perhaps one of the legally trained German forum members can address this issue as well. ;)