Luckily, I think competition is going to be making things better for the Australian ISP consumer. That, and recent improvements/additions in undersea cables.
I decided I prefer a limited plan where I know what service level (particularly latency and throughput) I can expect. For instance, plans with Adam and Internode are not that much more than a TPG plan for more usage than I'll forseeably use (I get 500gb a month or so at 20mbps + VOIP for $100), but the difference in gaming latency and actual speeds are both considerably more stable and faster than friends on TPG.
Given that your plan is 60% more than mine, I'll gladly pocket the difference and live with the minor problems I've had. As another poster mentioned, I chose to vote with my wallet. Generally small quotas + absurd off-peak times (where the majority of the quota is allocated) make my blood boil and I'll support anyone who helps break up the status quo.