TBH, I'm not sure about this.
Tolkein created a world and the languages that went with it.
While the sheer scale of his creation beggars belief ( I've actually met people who think this was based on fact
) it's only world-building, as JD said, a tool rather than an end in itself.
There's also the fact that, compared to the stories he set in his world, it's boring.
Creation of languages is an interesting mental exercise, but LOTR, as the final result, has given far more pleasure to far more people than the fantasy equivalent of Klingon ( and Harrison got it right when he suggested that learning Esperanto'd be a far better use of the reader's time).
For those who are interested, it's an interesting diversion, but hardly of world-shattering importance.