Is it just me, or does his look quite a lot like a population density heat-map? XKCD 1138[1] comes to mind.
For those persons concerned solely about light polution, this is definitely useful. But another thing I think would be interesting is this map, corrected for population density. Mentioned down thread is that different localities have different rules affecting lighting, and that this can be seen in the map. Correcting this map for population density would probably show that even more.