Several of those became staples of fiction because of their association with World War II, so this is sort of like complaining that Shakespeare is full of cliches. If the Nazis had eaten Jews instead of putting them in death camps, the past 70 years of fiction would have been full of cannibal stormtroopers.
Suppose I told you that I knew for a fact that the following statements were true:
You’d think I was crazy, right?
Now suppose it were the year 1901, and you had to choose between believing those statements I have just offered, and believing statements like the following:
Based on a comment of Robin Hanson’s: “I wonder if one could describe in enough detail a fictional story of an alternative reality, a reality that our ancestors could not distinguish from the truth, in order to make it very clear how surprising the truth turned out to be.”1
1Source: http://lesswrong.com/lw/j0/making_history_available/ewg.