Elves, Dwarves, Giants, Goblins, Pixies, Nixies, Dryads and Snyads should definitely not have Type IV names like Elberenthon Autumnleaf or Bordan Stronghammer but they should have hokey, folksy names like "Green Jack," "Weeping Annie," or "Big Ted."
Also, prompted by the AD&D Demi-Human Level Limit discussion over at Rients' joint; my view is that you have to keep in mind that these aren't people we're talking about; they're demi-humans, some of them don't even have souls. By D&D standards they're practically monsters.
And, ultimately, they're also critters from fairy tales. I like fairy tales, and if I was an adventurer I would be terrified of facing something from a fairy tale. I can handle fairy tale beings being badasses. But can I handle them being the most-badass mofos? The Conans, The Gandalfs (okay, he was an angel; in human form), The Gray Mousers, The Rambos, The Darth Vaders, The Snake Pliskins? The Batmans? The James Bonds?
No; they are from fairy tales. Only the children of Adam and Eve are allowed to become the King Arthurs, the Alexander the Greats, the Merlins, the Solomons, the Moses', the Musashis, the Indiana Jones'. I think that in almost every supernatural worldview, there is the idea that there is something that makes human-people and the super-natural spirit people of the woods and mountains fundamentally different. And the greatest legends are about human heroes (and also deities).
Demi-humans get unlimited Thief advancement because it's a crap class, and I'm okay with fairy tale beings betting top-shelf, triple-A level tricksters.