The most obvious improvement they could have made would be to vary the transmitter's power so that they could create a (very very approximate) circle of light a

The most obvious improvement they could have made would be to vary the transmitter's power so that they could create a (very very approximate) circle of light around the transmitter point. Raise and lower the transmitter power, and you increase and decrease the size of this light circle. Great for pulsing, explosion style effects. Different transmitters in different locations could trigger different colours. Thinking further, they could have introduced multiple low power transmitters across the audience, or highly directional transmitters pointing at the audience from a central spot. You could then create colour clusters, rainbows, spinners, rather than just a uniform effect.