Virtual reality is supposed to transport you into other worlds in such a way that feels like you're actually there, suspending disbelief for but a moment. While products like Oculus and HTC's Vive have certainly come a long way in terms of realism, particularly by improving screen resolutions, but there are still limitations.
Notably, the headsets can track your position as you move around your room so that you can naturally walk in games. But if you're like myself and live in a small apartment, you'll constantly be running up against the walls of your player space and be forced to resort to using joysticks. The illusion of being elsewhere is broken. Stick-based locomotion is an immersion killer.