I'm not sure why it should matter where one is when one performs a gesture. If I'm sitting on the couch I certainly don't want to have to stand up to adjust the lighting. Everything gets smaller until it eventually disappears, and the future versions of Echo etc. will just be integrated into the ceiling or a "smart" shirt or whatever. One won't have to worry about where they are, unless one wants to have a conversation without FBI or the spouse hearing it.
