It's really unfortunate. There's a great book called Metaphors We Live By [1] that digs into this same observation, using "arguments" as an example: you "attack" another person's argument, you "defend your point." You either win or lose. We could have just as easily chosen arguments to be a dance instead of a war.

A lot of narrative here in America eventually turns into good vs. evil, and War on X is an example of that. I've heard people attribute this to anything from religion, to the revolutionary origin of the country, to military-industrial conspiracy.

[1]: http://press.uchicago.edu/ucp/books/book/chicago/M/bo3637992...