When every Angeleno got to see the Milky Way, some called the police to report strange lights in the sky:
https://www.nytimes.com/2008/08/31/business/31essay.html
That, more than anything, emphasizes the need for black skies. We can't live with out backs to nature.
The article (disable javascript and reload to read it in full) also discusses the benefits of dark skies and the costs of not doing so (2008): "The Dark-Sky group estimates that badly designed outdoor lighting wastes $10 billion in energy a year."