New Zealand arguably has one of the best examples of democracy in the world.
With that considered, why would putting heavier restrictions on firearms be a bad thing?
In a civil society, with a very civil majority. Why would the society as a whole, object to stricter gun laws after what happened?
Maybe i'll end up eating my words, but i really can see them successfully implementing positive changes. They are a great democracy after all.
The issue with your belief, is some people DO need guns, as a tool.
Also some people are just bad people, through and through. Nothing will change what some believe, but we can certainly make it harder for them to carry through with things like mass shootings.