I wanna be a cute anime girl, dammit!
Doesn't some of this assume that we'll be using physically representative avatars?
It wouldn't eliminate many of the tracking parameters mentioned, but could one's motion parameters not be tracked locally, mapped onto a standard skeleton that is the same for everyone, and only then transmitted to the data harvester? Most games use one or a small set of standard skeletons to animate avatars, so I imagine this already needs to be done at some stage.