The preview videos for both Oblivion and Skyrim used the gravel voiced Dunmer as a placeholder, I have a feeling that maybe the voice actor is someone working at Bethesda and simply isn't willing to destroy his larynx with doing a whole game's worth of VA.
I was pretty let down when we got the Cockney Dunmer in Skyrim but I got used to it, I'm happy with the idea that they're a long way from Red Mountain and the Tribunal