I was honestly fine with time travel until ENT. I felt like the "temporal war" actually weakened the Star Trek universe. Because it means in every age, there's 29th century technology running around. It takes the mystery out of exploration for me -- you're not forging a path for future generations. Those future generations are there alongside you, making sure you are on the "proper" historical path. Just bugs me. Again, don't want to diminish any enjoyment you get out of time travel episodes. I just wish they would be more self-contained, and serve a specific purpose within the narrative structure of that episode. And not be the purpose. If that makes any sense.