Electric Chairs, Anyone?
Getting the display to react quickly enough to head movement is still not good enough. The real problem is in-world movement such as walking, running, driving, flying, roller coasting, etc. with NO corresponding head movement, and only a motorized chair can mitigate that.
Ever wondered why Lars von Trier's films nauseate you (apart from the genital mutilation, of course)? It's simply because he and his Cinéma Vérité predecessors insisted on the use of hand-held cameras to emulate the real-life experience of seeing things. Except that they don't at all because, as you move around, the ear's vestibular system provides inputs to the brain that compensate for the movement and cause you to perceive a relatively stable field of vision. Similarly, a motorized chair can at least in part provide the necessary vestibular stimulation for you to comfortably experience in-world movement, and over the years it's got quite good in terms of suggesting 6 degrees of freedom of movement whilst its base stays firmly rooted to the spot.