My first thought is that if they were two wireless pieces, then timing of the receiver could be an issue and it could see key strokes in the wrong order(?)
I guess power is also a thing. Perhaps it would require two usb sticks a receivers?
I've been keeping an eye on these discussions for some time and seeing some that are so close to my vision of a perfect design, the wire in between the two pieces limits one of my use cases.
Noticed mention in the thread about "Let's Split" - a quick search shows some pics that appear to show some without a wire between them, so maybe it's an easily solved issue, or could be trick photography hiding the in between wiring(?)
Glad to see more and more people working on better keyboard layouts!