AtomicmPC.com.au has a featured article summarising the past issues that the lack of R rating for games in Australia has caused. It details who the Office of Film and Literature Classification (OFLC) are, what they do, and have done. What the OFLC cannot do, however, is create a R classification, but they have voiced concern and conducted research numerous times on the matter, with the earliest being from six years ago...
"A 1999 report commissioned by the OFLC pointed out inconsistencies in the classification regime's lack of an R rating for games: 'Games that contain themes or other content which may warrant restriction to adults only are not currently permitted, even though comparable content in other media is permitted. It appears anomalous, and without scientific basis, to treat one medium as different from others in this respect.'
The article also outlines some of the recent attempts to create an R rating, with a possible push by the Victorian government in the near future...