I don't mind so much time travel and temporal stories by themselves, so much as the idea that a future Federation will have "time cops" as seen on VOY to protect the "proper" version of history. Mainly because I think that level of technology is too prone to abuse if it's used by some less ethical faction, and because of the assumption that only one version of history can be proper.
I forget the exact episode at the moment, but there's the one where Voyager has do deal with an evil, insane Braxton from a possible future as a result of his earlier contact with the ship. Which leads into a scene where the present version of Braxton (who is not dangerously insane) is arrested by his partner for the crimes his future self is "going" to commit.
From the perspective of a historian, it's been my experience that a lot of the fun is in the smaller details and how they interact to form a larger picture. There are many essentially great events throughout history, but no event happens because it seems preordained. Rather, the results are significant because the small details could have just as easily caused a much different outcome. Gettysburg was a crucial victory during the American civil war because the Union ultimately won, but they almost didn't win. They succeeded instead of failing, and that success allowed them to gain an essential momentum that would help in the final victory.
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