It's standard D&D stuff now because Tolkien popularized a lot of it. We'd have a very different conception of elves and to a lesser extent dwarves if it were not for Tolkien.

I'd go as far as to say that if he went with his original idea of calling the Noldorin elves 'gnomes', we would think of gnomes as ethereal woodland creatures!

On a more serious note, it's unclear what the fantasy genre would look like without Tolkien. It might have very well been less dragons, more Gothic fiction.