Murdoch apparently didn't offer any explanation for the delay, but this article suggests it's because it's becoming clear that not all news outlets will get on board. The Guardian, one of News Corp's biggest competitors, has committed itself to keeping things free, and the article also offers this:
Media commentator Jeff Jarvis has previously said that the only effect of Murdoch's papers charging online would be to clear the path for competitors. Some specialist papers can charge, he wrote in the Guardian, but "for most, pinning hopes for the survival of news on charging for it is not only futile but possibly suicidal."
I have previously made this argument:
It would be passing strange to assert that "news wants to be free." It's less strange to assert that people want their news to be free. Less strange still to assert that democracy wants news to be free, despite the capitalist tendency to charge. Even less strange to assert that in a free, democratic society dedicated to democratic ideals, more news, made more freely available to a broader public, is better than the alternative.
Additionally, it turns out that I have deep faith for the journalists, editors, and media chiefs who commit themselves to a dying profession out of a deep commitment to democracy, free speech, and interest in arming citizens with information they need to resist, decide, embrace and challenge cultural movements, laws, and norms. I just don't happen to trust folks like Rupert Murdoch, who by all appearances does what he does because it got him filthy rich and kept him there.