For one there is this thing called a power-law which required the voltages to be significantly higher than those needed to make a system like this work in a laboratory, the other is the breakdown voltage of the atmosphere, which causes any voltage in excess of this to return to ground, frying whatever it finds in its way (think lightning).
It would have made for a hell of a display piece.
Of course this does not stop Tesla groupies from claiming the government suppressed the design.
On another note: regular radio frequency transmitters put out enough power that so called 'crystal radios' can be powered by the transmitter directly. So in a way 'the system works' but the amounts of power that you can draw from it are minute. Tesla claimed that you could run regular industrial machinery from his technology. There is a funny parallel between the Tesla story and uBeam, the dreams are remarkably similar. 'Wouldn't it be a good thing if wireless power with substantial power transfer existed?'