I am not sure about these. 

They take up a lot of space. The materials are always going to have a high cost and they don't solve all the problems and actually create new ones.

For example, in Super hot VR i frequently end up crawling, even lying on my back to hide/shoot while avoiding bullets. A pad that can give u this amount of space would be prohibitively large and the floor tracking would really struggle to tell what is going on.

The safety bar is always going to be either a) restrictive or b) in the way. Bang, ouch or crack.

I haven't tried one but i suspect with a wireless headset the impulse to do a quick 180 to fight off an attack will be quite strong. I would be impressed if anyone could remain upright without a harness in a game of CS:VR (hypothetically)

Movement on the spot with foot/knee tracking and/or arm movements can inform the game that you are walking/strafing/jumping without any of the above problems. I actually do pretend walking to help with motion sickness in the less comfortable games.

It is best at a public arcade with limited space or for certain types of games but what will support for this look llike? I just don't see enough adoption / sales combined with developer targeting the device for this to ever take off. Even if the input is abstracted so the dev's do not need to code anything to support it, they still have to test it with the gameplay.

Agree or disagree?

In general, if something adds to the requirements, or takes up space, or has any other cost involved, those things make the technology harder to spread in the public.  When they are unobtrusive or take very little space or offer side benefits, they have less difficult spreading.

Today's room-sized VR kits are a burden, and as fun as Vive and Rift are to play with, the floor space cost is prohibitive to many people. Smaller devices (that don't require a room or large play area) are finding commercial success because people want the experience but are unwilling to pay the cost of a room.

An omnidirectional treadmill has an even larger cost because it can't easily moved, cleaned around, nor put away when company comes. It is out of consideration for all but the most dedicated VR enthusiasts. As you mentioned, there may be arcades and game centers and other businesses that set them up, but they won't be in every living room like game consoles (which attach to a TV you already have).