Why hasn't "Patterns of Force" been widely aired (it was made available as a pay-per-view episode previously) until now? The official reason is that later in the episode, the Nazi era is described as "the most efficient society” in Earth's history. But widespread consensus is that the extreme hesitancy regarding "Patterns of Force" mostly has to do with what remains the shocking and startling image of James T. Kirk in an S.S. officer's uniform (along with Spock's similar attire, before being captured and tortured in the only scene in Star Trek history that has Leonard Nimoy without a shirt).
Maybe not as fun a watch as is "A Piece of the Action", the other classic Star Trek episode about cultural contamination. And I remember one of the episode's own creators calling it "pretty hokey" in retrospect. But even so, that "Patterns of Force" (read more about the episode at Memory Alpha) is finally getting serious airtime in Germany is a pretty fascinating thing.