Ah that's the Australian Ofiice of Film and Literature Classification for you.
Those huge colour coded ratings things were only implemented in around 2005. Pretty much around the time I stopped buying R4 dvds and only buy R1 or R2 dvds online.
Many collectors were not pleased with it as you have noticed it screws with the aesthetic of the cover art. Nor does it match the rest of ones collection. But what can you do it's the governemnt. They refuse to implement an 18+ video game rating, they're not going to worry about making dvds ugly.