As far as UI goes I can see it being a keyboard to your mouse. Some UIs like menus are actually easier to design and interact with in a 3DOF plane.
But as far as hardware goes 3DOF is just a stepping stone; we only use it because it's easier to make. Once good, efficient 6DOF is available we can pull 3DOF out of it whenever we need to.
Comments
As far as UI goes I can see it being a keyboard to your mouse. Some UIs like menus are actually easier to design and interact with in a 3DOF plane.
But as far as hardware goes 3DOF is just a stepping stone; we only use it because it's easier to make. Once good, efficient 6DOF is available we can pull 3DOF out of it whenever we need to.