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While I think it's important to change things up in fantasy, I don't think using the name of one thing for something that is completely unlike it is a good idea. Making your goblins be basically elves will simply confuse people, and if you're going to come up with something completely different, you might as well come up with a completely new name for it. A certain amount of hate for Twilight came about because Stephanie Meyer co-opted the use of the word "vampire" for something that really barely fit the description. It seems like fantasy is a very traditionalist genre, which isn't so surprising since, in a way, it's been around for quite a while.
This is me not being offended that you just equated me with Stephanie Meyer. Am I not gracious?
More seriously, I think you missed my point entirely, and instead are letting yourself be bothered by an idea just because it doesn't derive from J.R.R. Tolkein's work. Elves, goblins, trolls, boggarts, dwarves, and so on were just different names for the same idea; mischievous little sprites who troubled people in folklore. Making them pretty and welcoming on the outside, but cold and cruel on the inside fits right in with their folklore origins... but because it doesn't agree with this established "fantasy standard," some people would have conniptions over this.
Point of interest; the name and idea behind Goblins comes from German Kobolds, which in turn are derived from Greek Kobaloi, the randy and mischievous sprites in service to Dionysus. The fact that Goblins aren't still horny, shapeshifting alcoholic faries is a complete violation of Goblin cannon... but I'd bet few people are troubled by that.
So yeah, long story short, Fantasy has been codified too heavily, which stifles creativity and bogs down storytelling. To me, having an accepted "fantasy standard" seems like a violation of the whole purpose of folklore and fairytales; to tell an obviously untrue story to others, for their entertainment and/or education.