The funny thing about it? While it's still only a fraction of our continuous global energy usage, even just an hour, if the entire world actually took part, would save a good deal of money, energy, and resources.
I think the problem is it's too infrequent. If it was a set hour each week, people might get into the habit and the effect would be 52 times greater per year as well. But once a year? It's like daylight savings time, out of sight, out of mind.
~Dune~