[kaisen99]

I would say form factor + input controllers + availability. Current headsets require way too much setup. High end headsets are tethered to beefy PC's that require a painful setup process(for most). The low end headsets require certain android smartphones(not every smartphone works with Oculus Gear or Daydream for instance and nothing works with Apple except Cardboard) and are also cumbersome to pair with controllers and place in the headset properly.

A standalone cheap headset is a step in the right direction, however something like Santa Cruz with 6DOF is when I believe more mainstream adoption will start occurring. Right now the most widely available headset is still Google Cardboard.

Input is making progress, but I continue to think using your hands would be the best option rather than any controller.