Reducing unnecessary illumination has many benefits to society. First, expensive energy resources are conserved, lowering demand and helping stabilize prices. Less waste heat is pumped into the environment, not that we couldn't use some as these record cold months continue. :)
Less dependency on resources from troubled nations and the political entanglements that follow. Plus, we get to see the skies and the wonders of nature are visible to all. I don't know why so many green fanatics suddenly become illumination advocates when the issue is their own neighborhood. Walking the walk is uncommon. It's more fun to legislate what YOU must do.