Paying people to criticize your work is a great idea. You are getting a benefit, and the mechanical turk collects people who want to be involved. When you spam your friends for feedback, since they are your friends, you'll get responses similar to your own world view.
BTW, using age 18 as an arbitrary breakpoint for responsibility has never made much sense to me, especially since in the south, the legal age for the idiocy of your choice varies from state to state.
HBO did an addiction special about 3 - 4 months ago where they gave a compelling reason for blocking children and teen's exposure to mind altering substances. The brain is still growing and maturing even up to the teen years, and when those individuals substitute nicotine, alcohol, etc. for coping skills, their brains stop maturing. Even worse, functional MRI scans can show differences in neurotransmitter levels between addicts' brains and normal brains.
The younger they are, and the worse their coping skills, the more likely they are to become addicted, rather than a casual user. So attempting to block their exposure would have a payoff if they are likely to become addicted at 12, but less so at 18.
Medically, the cutoff point for vulnerability to addiction in normal adults seems to be age 30. Your argument seems to be based on the idea of ROI for restriction of choice vs the number of people affected. Implementing such a ban would just be prohibition again.
I'd be interested in reframing your argument around the factors controlling individual's choice to try a cigarette. Exposure to advertising, peer pressure, product placement in movies, would have to be balanced against the person's understanding of costs, health risks, the difficulty of dating a non-smoker, and teenage belief in immortality.
And that brings me back to age 18 again. By that age, the majority (say 85%) of non-addicted teens have completed the final brain growth stage and can analyze their own thought processes, especially decision making. At 12, almost none of them have that capacity.
Pushing the legal age up to 21 would only get you a few percentage points of gain, either on the addiction resistance, or brain growth sides of the equation.
Putting the effort into cutting out the pro-nicotine propaganda, providing the information needed to make an informed decision, and coaching on decision making skills would pay off better.
Getting back to the people who lost you along the way. I think some may have just not read all the points, but others may have seen the issue in a different light, and thus only responded to part of it.
