Belf girls are too thin though. As inaccurate as the Nelf model might be, it's at least got the right physique to be Sylvanas. The flouncy Belf animations don't help either :P
Besides, look at Manga Sylvanas (http://www.wowwiki.com/Image:Sylvanasmanga.JPG), from the Ghostlands Trilogy (http://www.wowwiki.com/Image:Manga_Sylvanas.jpg), and WC3 Sylvanas (http://www.wowwiki.com/Image:Sylvanashelf.jpg).
I prefer to think of it as simply that Sylvanas's elfy-size makes her MORE badass in comparison. It's east to be a bruiser when you're the size of a truck and your weapon's the size of a telephone pole (I'm looking at you, Cairne).
Besides, in fantasy settings, elves are as a rule more slender and supple than humans (+2 Dex, -2 Con), and her renown was as the Ranger-General and the best Azerothian archer, not an Arms warrior. (Oh wait, TG, Fury now). So I'm perfectly willing to credit the belf model, which is also in use for high elves in WoW anyway, which is what Sylvanas is (and therefore, the body she reclaimed).
:)
Of course, this isn't to say I think elfy-belfy standards of beauty are the only one. Female-orc bashing annoys the heck out of me, given that some of them are damn hot (http://www.wowhead.com/?npc=8587#screenshots:id=24026).