Great post, but it is not just the Brumbies, it is the whole Australian Rugby conference. The Brumbies have the lowest error rate and hence lead the conference, but that isn't much considering the competition. I think the Brumbies still have a positive PD +3 IIRC, which is a very sad indictment on the state of Australian Rugby when you consider they are by FAR the best.
You have identified the same issue i believe is the key issue holding Australian teams back. Aussie rugby is so worried about making errors that play themselves out of the game. Its a mentality issue, and an issue coached and trained in to them.
Aussie sides are consumed with defence and as such won't take the chances in attack. This is where the structure issue stem from. Good defence relies on good disciplined structure but that has been so well ingrained its entrenched in our players its habitual, and in game plans and has become so ridiculously predicated on the concept (arguably obsessively) that its used as a platform for our attack which has lead to it being is basic and predictable. Mick Byrne has clearly identified Aussie rugby can play unstructured, and its also been well proven on the rugby field when we play Kiwi teams. IMHO, this is the root cause.
Kiwi teams and even the Lions take an approach that to out score you they will take chances that will lead to errors that will cost them points; but the rewards are more point than the blead so they know will outscore you doing it.
Have a quick look at the way the Kings and the Sunwolves played on the weekend. They are now progressing far more than any Aussie teams and starting to mix it with the best by taking the risks to get rewards.
Nothing will change until we get fresh blood in the coaches box. As for the current crop of coaches like Larkham, they need significant time away from Aussie Rugby to break the habits and moulds, and mentality and get exposed to see things from a new prospective.
As for the Larkham player criticism, I certainly don't agree, and I think with some fresh prospective he could be a really good coach.