I love time travel in fiction.
That is one of the main reasons why I love Doctor Who.
I love how this storytelling device can put ideologies from vastly different cultures, separated by decades or centuries, up against each other. By doing this, we can compare them, and find strengths and weaknesses in both. It can also just lead to funny jokes, or cool imagery, like a medieval knight riding on a velociraptor and wielding a laser sword.