Since the crux of the pro-gun argument relies on this idea that more guns will bring down crime, once this is shown to not be the case, there's no reason to have them so widely available.
If you have no effect either way, shouldn't one err on the side of individual rights instead of spending extra money to unnecessarily restrict them?
What about my individual right not to be around guns, which kill thousands every year by accident? If they're not going to cut down on crime either way, let's restrict them to cut down on accidental deaths.
More people are killed on the highways than by guns.