It's not just this, it's a pattern of behavior in general by the Australian government. It's not even a single action, I don't play games that often anymore and the lack of an R18+ classification has almost no effect on me, there are many data points in Australian political actions though which reflect a deeply troubling underlying truth, the government perceives it's citizens as children.
My reasons for leaving are many, but the two big ones; primarily the above, but secondarily that I can't help thinking in a large amount of cases with regards to aforementioned citizens, the government is not entirely wrong.
So long Australia, and thanks for all the fish.