Even for big events like the Lions test or the Bledisloe, the only way that Etihad or the MCG can possibly filled is relying on away supporters, which is just embarrassing. Play a game at the MCG if you want to throw away home advantage, you can guarantee there will be more Kiwis there than home supporters like in previous years.
You make it sound like far more of the crowd would be supporting the Wallabies if it was played at a smaller stadium. What's your logic? Are Aussies better at using Ticketek so can snap up the tickets faster than the away team supporters?