One could blame Tolkien for the first and assorted writers for the second, but -- Tolkien had dwarves, too. And hobbits. And ents. They didn't take off the way the elves did.
What is particularly deplorable is that they are often humans with cosmetic traits to tell them apart. Elves have pointy ears, vampires drink blood (except they often don't, at least on stage), werewolves get fuzzy. . . . In fine it often comes across as this is short hand for "cool" in its various forms. Especially if you've read a wide variety of primary sources, which I strongly recommend for all aspiring writers, but which does lead to the consequence that you've read works by humans considerably more different than you than the typical fantasy elf/vampire/werewolf, so the difference is particularly flat. (Tolkien was a bad influence here. His elves could be eerie and numinous, but he made them more human than many another writers, and others continued the trend.)
Very early in my writing career, I worked out a question for myself: Is this elf necessary? And if it wasn't necessary for him to be an elf, he wasn't, and there were, in fact, no elves at all in the story. (Note that if you have elves, or dwarves, or trolls, you can make a character one out of a frolicsome love of seeing what effect that will have. Indeed, if all the main characters are human in a world with non-human species, you may need to explain it. But you don't need to explain why the world is human only.)
Yes, you then need to make your character elegant, emo, feral -- but in my experience writers on the whole do a better job of making the character such when they aren't counting on the stereotype to characterize for them.
What you do see writers doing in stories with or without non-human characters? What favorites do you have for both?.
part of bittercon</lj> .