I guess Andu that if mandatory offset tracking were to be implemented, that airspace in Aus (and indeed the world) would have to be completely redesigned starting with the terminals. A lot of the airspace where I work is designed around aircraft being on track give or take 1/2 a mile, and the resulting off track scenario means that separation standards may not be provided.
Thats no reason not to implement it, but did anyone ask if either of these aircraft were track shortened any length? if they were then they may have not been on an air route and offset wouldnt matter at all. *generally* if things are kept on the rails, these types of things tend not to happen (having no idea the lead up to the incident).
Were the aircraft within surveillance coverage or was this a procedural error? There is a lot to consider before people start getting their pitchforks out.