Perhaps we are asking the wrong question. If we do not restrict guns, then how do people propose to lower gun violence? It may be on the decline, but it still is a problem.
I'm curious to see what people propose.
While I'm all for gun control, the US is still special when it comes to gun violence. There's many other countries where citizens are allowed to own all sorts of dangerous handguns and rifles, yet they don't have the same levels of violence as the US, which indicates there's many underlying problems that cause people to want to use their guns in bad ways.
Personally, I see the biggest underlying cause of US violence as the massive level of inequality between citizens...
I think Frob explained the overall reason for gun violence being higher in the US as compared to other countries where guns are legal pretty well. The underlying reasons are hard to get at. The NRA tends to blame media, while liberals point at guns. The fact is that neither has better proof than the other. We can look at examples that seem to disprove both. Many countries have the same media that the US does, yet violent crime is not as high. At the same time, there are countries that have freely available guns, as you pointed out, but not nearly as high a violent crime rate. The truth is that much of the gun crime is gang related, and the reasons people join gangs...I'm no real expert there.
It may be simplest to make guns illegal in urban zones while letting them remain legal in less urban areas. I think someone suggested this earlier in this thread. The more urban areas do not have the same need for guns that people may have in more rural settings. In more rural areas, I can see why people would want to keep guns, even though I personally do not like the idea of freely available guns.