Remember how in the 90's everything was EXTREME? Often with five or so X's or leaving off the E just to show how XXXXXTREME they were?
3D is just that for the 2011-2020 decade. They think they burned out the public on HD too quickly, so they needed a new gimmick to make their products superior/more expensive.
Why add a third dimension when we still have much to explore of the 2nd?