The 'two points for the bye' gets a bit of grief as to why? But my theory is this:
If every round is cancelled and each team is awarded two points for games not played then the team that had the bye is unfairly punished. In a tight competition it could mean missing finals or losing a spot on the finals ladder, or the spoon, or the minor-premiership. By allocating two points for a bye regardless it avoids this scenario.
The whole round could be cancelled because of a terrorist attack, weather event, etc. It's highly unlikely, of course.