Com relação aos ouvidos pontudos dos elfos de Tolkien:
It's a tradition that goes back to Victorian and earlier presentations of the faeries. The faeries in these old pictures all had pointy ears, and Tolkien retained that trait; in the old versions of his legendarium, the faeries of England were either degenerated descendants or misguided representations of Elves of Middle-Earth, so there were some traits shared between the two.
No que diz respeito aos vulcanos, isso foi respondido aqui:
Gene Roddenberry wanted a slightly satanic looking character. He's never explained why, but he liked the look.