It's important to note that rugby circa 2003 was an outlier in terms of popularity (as per gigantor's number 3 in his post that just appeared).The decline of RU in Oz in the past 15 years has been staggering.
The 2003 WC was a major event in Oz; even in Victoria it created huge interest. I recall the Oz/Eng final getting astonishing FTA ratings that iirc was superior to what SOO and AFL GF can't reach. I recall even members of my own family who usually had no interest in the sport watching the 03 final.
It would've been unthinkable that the sport could decline so rapidly in less than 20 years but here we are. I'm just curious as to what the prime causes of it are. Obviously the decline of the Wallabies (especially their constant Bledisloe failures) is a factor, but it shouldn't be this severe.
I recall on the Titus O'Reilly/Sergio Paradise podcast they discussed why the Melbourne Storm have gained a much better foothold on the town than the Melbourne Rebels. They observed from personal experience how when interacting with RU types who were supposedly trying to entice Vics to get on board they were largely full of contempt and complacency. So perhaps that insularity and snobbishness has been a constant problem for them.