Ms Bennett said she was "absolutely astounded" by the extent and quality of feedback from the meeting.
Ms Bennett is making a tour urging more public submissions on the Government green paper.
Concerned individuals and community groups have until February 28 to make submissions.
The green paper says that the Government had "worked hard to make improvements for vulnerable children", but that about 15% of New Zealand children are "at risk of not doing well".
About 50 people, many of them representing government-funded social service providers, attended a 6.30pm feedback meeting at the Dunedin Public Art Gallery.
Ms Bennett said considerable efforts were already being made to protect vulnerable children but the outcome, including some cases of severe abuse highlighted in the news media, was "simply not good enough".
An intense meeting followed, running over its initially allocated 90-minute duration, participants having for part of the time broken into six groups to consider some key issues in detail.
Positive changes were needed but mandatory reporting and increased information sharing were sticking points for some.
Some people insisted that children were entitled to basic privacy rights, and that some parents fighting to turn their lives around could also be misunderstood.
Anglican Family Care Centre director Nicola Taylor, of Dunedin, warned that some of the highest risks were actually being faced by families whose members had not been seeking help from social services.
