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The issue of full cut-off fixtures is basically over, although the lights at Kellyville are the first I've seen recently using drop lenses. The real issue is spectrum, for both the purposes of astronomy and health the evidence against blue light at night is mounting strongly.
The amount of light from a luminaire that enters the sky has been pegged at 3% for a long time, and full cut-off fixture put that to zero. The issue is that 30% of the light from the luminaire will be reflected back up into the sky, and then a certain percentage of that comes back down to be collect by your eyes or the telescope.
As the population of urban areas increases and urban areas expand it is imminent that the amount of lighting will also increase and that light pollution increases. The situation can only be dealt with by lighting only where necessary and with the appropriate amount of light for the purpose.
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