Responsible people should be able to buy a gun. I'm not an advocate for the sort of wild west world the NRA wants. And I believe in extremely careful screening and limits on what people can own (I do not think assault rifles have any place in civilian life, for example).
But people out in the country, for example, who hunt for food or don't have any cops around have a legit reason to own one.
We make concessionary decisions in a society all the time. There's all sorts of things we allow that have even less rationale than guns (alcohol? Does anyone 'need' it?).