They haven't "dropped" it. it has been made far more workable and sensible: i.e. on roads more than 90km/hr the onus is on traffic to slow appropriately and provide space. Additionally on roads with limits less than 90 the requirement to drop to 40km/hr is still there and has in-fact been expanded to include NON emergency vehicles such as towtrucks and breakdown assistance vehicles.
An unusually bright piece of common sense in my book that could be tweaked further, the idea that vehicles could slow to 40 in a 110 zone was just stupid and we are lucky that it didn't cause more accidents (I read of at least one - in victoria not long after they started their rule). I experienced the situation myself where I came over a blind crest at the speed limit only to see a cop with a customer on the other side of the road. I rolled off but there was no way I would have been able to safely drop to 40, much less if someone had been behind me. Even from 80 washing off half your speed in a short distance with someone up your clacker will be down right suicidal.