I don't buy the limited player pool argument. As the graph in the attached table indicates, Australia has about 39,000 senior rugby players out of about 86,000 players overall. There's about 200 professional players spread over the 5 super teams, plus plenty of talent in semi-pro competitions in Sydney, Brisbane and Canberra, plus quite a few talented players who are playing professionally in UK or France.
 
http://www.rugbydump.com/2011/09/2103/rugby-world-cup-daily-player-numbers-around-the-world
 
Multi-skilling is fine in the development/academy phase where you are giving players generic skills. As you enter the team/squad phase, there needs to be a degree of specialisation. This is one of the reasons why development should be in the hand of the super teams where they can receive specific positional development, rather then in the generic HPU type environment.
 
Weakening one position to strengthen another has rarely worked long term. Australian backline play, which was once our pride and our strength has never been in such disarray. Some of the players are much more talented than they are showing, because they are being shuffled around into different positions with different combinations.