Cool idea. The generator is a means to an end though - to create a diverse martian population for the game's mechanics and settings. I'd do things differently if the focus was on build-a-face. Not that it couldn't work but it'd be a different game.
For the mouths, you're on point. I haven't shown it yet but each mouth has 3 versions: em/oh/eh, which is just barely enough for animating speech.