I think this guy has it correct:
One reason “Live Earth” was dead last in the TV ratings is the music was irrelevant to the target audience. In fact, music itself is rather irrelevant. what with Video games and You Tube getting more action. There is a reason MTV shows so few videos: Nobody watches them.
The other reason is that Woodstock was not organized by Hubert Humphrey, the immediate past vice president of the United States at the time.
The fact that everyone is already ‘aware’ of global warming makes it a redundant concert idea, too.