I don't think they're able to add new options to the "template" that each character has and gets transmitted to other players.

They can add more hairstyles because you can only have one hairstyle equipped at a time. But the "face options" (that for some characters are beards) are just toggle switches so the template is just "option 5 on/off" and they can't add an option 6. The most they could do would be to add an identical new face option with a different beard style.

That said, I think there is some opportunity that the devs could explore, because they've figured out how to make Hrothgar change hairstyles, which apparently is by switching out otherwise-identical faces in the back end, so there could be room to add one more option for other characters in the same way. Different horns for Au Ra, different beards for other races, things like that.