More realism and detail is always a good thing, and it's important to remember that we're still in beta -- there's no way those Gnome eyes will go live. Blizzard may even be updating the way the heads are put together as well, in order to make sure the new hairstyles all work the way they're meant to. The real challenge, however, will be making sure that the characters come out of this process looking the same way they did before -- if the textures look extremely different, you may end up logging into Wrath with a character you don't recognize.
Update: Don't panic -- Tigole says the facial model texture changes were "a development experiment," and these funny faces will never make the live realms.
Thanks to everyone who sent this in!