I question the safety of this design a bit. Constant rotation of the live and neutral wires could fray them. Also, it doesn't look easy to retrofit one of those plugs onto a cable.

I guess it is good for portability, but the constant turning of the neutral and live could end up damaging it.
Alternatively, if the plug is going to be plugged in for long periods of time (e.g. behind a TV) then the physical size of the plug is quite irrelevant.

Still a neat concept though.