As a link from the M2 to the Pacific Motorway, it appears to be a much needed road.
However, looking at the diagram, I noticed that no provision had been made for westbound traffic on the M2 to join the North Connex, nor was there any provision for southbound traffic to join the M2 eastbound.
Since the M2 is the only freeway north and westbound from the city of Sydney, that means there is no provision to travel to Sydney from Newcastle or vice versa using the North Connex.
You can of course exit to the Cumberland highway and then join the North Connex, but that would add two sets of traffic lights and queuing, which isn't what you want if you are paying for tolls on both the North Connex and the M2.
Right now, there is a lot of truck traffic from the Cumberland Highway to the M2 westbound at any time since the M2 and the M7 form the only Sydney bypass route for through traffic.
Could it be that they want to discourage southbound trucks from using the M2 eastbound to get to Port Botany? (and vice versa north and westbound?)
But there is a lot of traffic currently on the Pacific Highway that would use the M2 and North Connex if there was a direct connection north and westbound and south and eastbound at the Cumberland Highway.
The only thing I can think of is that such a transfer of traffic from the Pacific Highway would completely swamp the already inadequate M2, so the planners have decided that it is better to have this traffic on the old highway (passing most high schools, primary schools and private schools in the district) rather than completely jamming the already overcrowded M2.
It does make more sense than the West Connex, however..