https://www.ifixit.com/Teardown/Oculus+Rift+Development+Kit+...
I don't see how this matters at all. If a cable doesn't restrict movement, surely a table, chair, wall, mountain, lake, ocean, cliff will restrict your movement. You can't emulate infinite environments when stuck in the physical world.
From my own experience, working with a keyboard at a desk doesn't really work well, for various reasons. For one, it's pretty restricting to the movement, and trying to scale the tracking to compensate so you can view a full 360 degrees in a shorter head-swing is both still limiting because you can't perform multiple rotations, and is still extremely disorienting. For another, having a physical sensation of a fixed object that isn't reflected in the visual display also breaks immersion. Also, if you have you move your hands off of the keyboard at all (like, to adjust the display on your face), it's really hard to find it again.
There is currently no good way to do user input in VR. About the best experience I've had so far was standing up, using a bluetooth gamepad.
I think a lot of software innovation is still possible that will allow a VR headset to mask maybe a 50ms delay (smaller than in OP) with advanced algos, allowing you to get photorealistic, real-time graphics through low-power hardware that fits in the headset.