Australia don't really have an attacking alternative to JOC to play at 12, unless Deans selects Ioane out of position. Essentially all of the other options have a more defensive mentality - Fainga'a, Horne, Barnes, McCabe, etc.
Barnes had a horrific match at 12 but I don't placing him at 10 is the better option - and isn't that counter intuitive to your point about an attacking 12? Australia played an attacking 10 and defensive 12 on the weekend, and you'd rather a defensive 10 and attacking 12 - whats the big difference?
They did actually employ a similar stategy to what you suggested by kicking for territory and attempting to run the ball once in a better field position, and their aggression on defence was also, for the most part, quite good. They just weren't good enough as a unit to come close to winning the match. Which I still don't believe was a fault of...
...Robbie Deans, who it seems even New Zealanders think should step down. I still believe calls for his resignation are over critical, and those detractors should at least wait until the matches against South Africa and Argentina. At the end of the day, theres only so much he can do with the squad he possesses.