Whatever the OFLC may claim, the censorship system they are part of is not just about "protecting children". It is about preventing adults watching Pier Paolo Pasolini's Salo or reading Abbie Hoffman's Steal This Book. These and many other books, films, and computer games are banned in Australia. The Rabelais case and the banning of Baise-Moi are examples of what is wrong with the system. (Helen Vnuk's book Snatched: Sex and Censorship in Australia is a good overview.)
And lo and behold! Now (September 2000) they've banned a huge swathe of non-violent erotica because it depicts "offensive fetishes" (like spanking). The OFLC guidelines get tighter and tighter... Mapplethorpe's Pictures is now (March 2001) Restricted Category 1, following the usual beat up. (Note that this makes it illegal to sell Pictures in Queensland.)
And when it comes to protecting children, the OFLC tries to enforce the morals of a minority on everyone else's children. Witness the R-rating of Passion and the MA-rating of Southpark. I can see no reason why I would have been unable to cope with Passion at 15 or 17, and my parents certainly wouldn't have objected to me seeing it.