It would be simplistic to put this off on the organizers of the Australian festival known as the Big Day Out. Blur isn't exactly a solid performing and recording and touring act anymore. How's that album coming? You know, the one that was scrapped? Organizers for the festival have also had to content with problems of staging shows in smaller cities just to break even. They are victims of a larger trend--the music festival is faced with serious financial problems and people are being left hanging.
The Australian summer concert tour falls during the off season for the European festival circuit. Quite a few have had to be cancelled in recent years, much of it due to the fact that people aren't able to spend as much on festival tickets and food and merchandise. Let's face the fact that some of it is also due to the notion that music isn't as dominant as it once was. Costs are out of control. Festivals are being forced to price themselves out of existence. There is a lot of product but much of it isn't very good anymore.
Culturally, a music festival isn't the big impact ticket that it was twenty years ago. Music is being replaced by video games. Add that to the problem of widespread unemployment and spiraling costs and you have a damned good reason not to go see a festival show.