I think you have made some good points.
In the USA most of the country is Class E Airspace from 1200' agl up to 17999' and then Class A above that.
This means that for most people every single IFR flight can be done without ever leaving controlled airspace, except for maybe the last 700 feet before landing at your destination.
In Australia there is more uncontrolled airspace then not.
There are thousands of VOR's over here, although GPS coverage will probably alleviate that difference in the future.
The amount of Radar coverage over here is a great deal more then in Oz also. I also have had more then one occasion where a vector has made up for not being able to receive a VOR yet.
It makes life very easy.
Weasil