What the OP described would be extremely low bandwidth -- you only need three parameters to describe what to draw per keyframe (maybe one or two more if you wan

What the OP described would be extremely low bandwidth -- you only need three parameters to describe what to draw per keyframe (maybe one or two more if you want to describe mixtures of emotions or identities or more complex things), whereas you'd need more to describe 3D animation. It's not a huge benefit over what you're suggesting (realistically, when are your bandwidth constraints ever that strict?) but it's an interesting idea.