In my ongoing research on the subject of worldbuilding, I came upon this interesting TED-Ed video, about fictional languages.

Adding a functional ‘conlang’ to your storyworld will help storytellers out with creating the rich cultural diversity that can enhance the audience experience of visiting “another world”. It is a difficult and time consuming art, that doesn’t always seem worth investing by simply asking: “Why would I make a language that no-one can understand?”.
Granted, next to a fanatical few, no big audience is interested in listening to a story they can’t understand. But there are a few very important and world-enriching details that your unique language can add to your story.

The most direct functional use are the names you could use in a storyworld. Like in real-life, names have a origin in language and that origin usually hides a meaning. (Did you know my name Rudolf, for example has it’s roots in the Germanic language, meaning Famous Wolf. See Wiki Article for info: http://en.wikipedia.org/wiki/Rudolph_(name) )
Tolkien makes great use of this in his works, creating languages helped him generate unique and interesting names for the places and characters of his stories.

Discover more in this video or by checking Google for the term “conlang”.