Yoshi Interview at PGS

[BillyKaplan]

I mean, I can see why hair is easier to add then faces, faces have multiple parts to them that need to be rigged and animated to emote properly, while hair just need minor texturing and basic fluidity added to it.

That's not what he was talking about, I think. Actual rendering is client side so that's nothing the servers have to worry about. And I think most people agree that what Yoshi talked about wasn't adding more face options, but things like splitting the Au Ra horns into their own option. Adding sliders and categories, in short. Not because it'll be harder to render or anything, that's a client-side concern, but because if you're in a room with 100 other players, instead of X pieces of information the server has to send each of them so that they can render you, now they'll have to send X + 1 because the horns are their own category. And when you have a player run through Kugane or Rhalgr's Reach, that +1 they need to send out per receiving player in the zone starts building up, all the more so if you have more than the one Au Ra player in there.
In that sense it's a bit funny because they could effectively give you every face + horn option in the game baked into the face category, similar to how we have all sorts of hair options that differ from each other only by accessory. The old Y'shtola hair comes to mind where the beads are silver or gold, or the hairstyles with hair-bows. Extra options, same number of categories.