I see this change to dispense with the guest passes as a revenue gathering exercise. As a Koru member I could take three guests into the Auckland domestic lounge (providing I had guest passes of course.) Now I can take one guest for free. If I wanted to take the other two guests that would be no problem - just pay some money at the door. That fee is currently $25 per person. That's an extra $50 into the coffers of Air NZ. 'Nice little earner' to quote a television character.
As for children in the Koru. I am childless and I don't mind children in the lounges. I have never had an occasion yet when a child was unruly or out of control. I imagine the child/children have been read the riot act prior to accessing the lounge and are told not to treat the area like certain hamburger establishments.