Regarding your PS: I would wager that big city liberal politicians as a class are similarly afraid of gun owners caring about the second amendment.

Regarding the rest: I am ashamed of my not realizing today was the anniversary of prohibition, although I'm still not convinced the symbolic parallel is there. As far as researching violence in America, I would agree with you that there is a considerable amount of information out there which has not been acted on. But I think there's always more to know, and finding information that could be actionable policy suggestions would be worth the cost. It's better for everyone if the government can enact policies based on reason and science first, instead of an emotional knee-jerk reaction, as many people (admittedly, myself included) felt about impossibly tough, immediate gun control after Sandy Hook. Credibility may be an issue with government research but until we see more private organizations making an effort to research violence and its causes in an objective, peer-reviewed way, government efforts may be the best we have to work with. All research is, sadly, tainted by biased human hands. Personally, I think the CDC may be our most effective research body but I admit it can never be perfect.