You can also shift to more postures the farther back the display is and it will still take up roughly the same field of view no matter how you move, whereas with small monitors you can't both sit up straight and lean back without drastically changing pixels per degree of vision.
A constant focal point is not good for eye health either. I had considered converting my two monitor setup to one traditional monitor and one project that is > 10ft away. But projectors have too many disadvantages atm (e.g., high power consumption, brightness, etc.).
Perhaps an alternative would be to suspend a screen from a drone that is constantly moving around the room. It would combine eye muscle exercise with neck exercise. For extra points, the screen could be configured for me to chase after it, providing ever more opportunities for exercise.