If I had to point at a catalyst it would be the one Parsifal mentioned, there was a recent event in Sydney which resulted in the AFP arresting a bunch of fundamentalists who were talking about beheading a random Australian. So it seems the AFP are already listening to phone lines if they want.
The LNP are luddites through and through, in the past they have demonstrated their disdain and lack of knowledge in regards to the internet (dismantling the NBN for political points, metadata retention, anti-piracy legislation talks, etc). With the rising presence of ISIS in the Australian media, especially home grown terrorism (which, in part, is due to their own rhetoric), they have decided to expand the powers of ASIO and the AFP in the name of catching terrorists.