Cash, just got around to your question. I still consider myself a smoker (and always will even if I never smoke a cigarette again) and I think regulation by the U.S. Alcohol, Tobacco and Firearms agency was fine. I do not want the FDA regulating tobacco.
Note also that it's not just nicotine that the FDA might seek to restrict if given the authority over tobacco products. It can tinker with the formula all it wants, banning some ingredients and restricting others. There is no limit that stops at nicotine. It can order all carcinogens out. There are more than 40 in tobacco smoke.
While I don't favor the FDA regulating tobacco, I do think a case can be made for that agency regulating our e-liquid. Pure nicotine is a drug. We make recreational use of it. And it comes from China, with no assurances that manufacturing followed any standard (take our word, they say .. sure, but you're the people who killed pets and babies with industrial melamine). Trust no one, the X-Files taught us. In this case, the slogan fits.
Sadly, I think some regulation is coming and even necessary if e-smoking is to become a significant segment of the "smoking" population.