It's not essential, but it sure helps a lot, once you get to know the culture you will have a better understanding of "Why" things work in a certain manner, specially in grammar cases, I'm don't mean that you have to became a master in linguistic root or anything like that, but I'm sure that you have already notice that, when you begin learning a language is almost impossible not to get at least a little bit of the "taste" of the cultural side, regardless of the language. Also it really prepares you to when you actually visit or interact with native speakers.