I've not heard of it until I've just switched the TV on tonight.
So, to raise awareness about each individual caring for the environment and to remind us that it's the little things that count (switching off lights, making less journeys etc.) they decide to put on a massive worldwide concert, with an incredible amount of electric equipment and lighting. They get thousands and thousands of people to travel to these concerts, all the bands, all their equipment needs to be moved to the concerts.
It just doesn't make sense.