Here's a link to a New York Times article by Dr. Sandeep Jauhar in which he discusses the idea that people with good health habits should pay less for health insurance than those with poor habits.
The idea is one of personal responsibility, and the government's responsibility to "pick up the pieces" when individuals don't comply with medical advice. It turns out that it's just not that simple, of course. As Dr. Jauhar says, "When people advocate the need for personal accountability, they presuppose more control over health and sickness than really exists."
We like to think that if we each just worked harder at "good" health habits, all of our chronic health problems would be eliminated. If people just ate "better", exercised, didn't smoke, and had less stress, we would have less obesity and overweight, less heart disease and less diabetes, and therefore lower health care costs. It turns out that's not really true. Changing one's diet and exercise doesn't necessarily result in weight loss. The system is much more complex than that, and much messier! Americans want THE ANSWER to complex problems, tied up in a neat bow. The problem of personal responsibility when it comes to health habits is much more complicated than that.