As much as I agree with the sentiment of Gun control measures not being a strongest preventative measure, its still A preventative measure.
Only 3% of homicides in the US are a result of registered weapons. THAT'S STILL PEOPLES LIVES YOUR SAVING! Its not a policy based on opportunity cost, i.e if we change the rules to THIS instead of THAT then these people get more but these get less. Its black and white kids, introduce tougher gun ownership laws and you save SOME lives, not all, its not the root of the problem, but it still stops some people from being horribly murdered.
If anyone has seen 'Bowling for Columbine', Michael Moore suggests that the gun loving culture stems from a 'fear of the black man' and the ubiquity of guns sit in society. In movies for example, guns are often the strongest solution to any problems. Zombie movies are so popular because, with Zombies, all you have to do is shoot your problems away. Hero's require guns to be heroic.
Whilst I agree we absorb so much of american culture, there's still a massive cultural shock when you go to the states and walk passed every shop and some security bloke is standing there with a gleaming 12 gauge.