Yeah, but you can't punish people for getting sick, and we already charge people who smoke (etc) more.
People who smoke don't get charged more, not under any employer/group health insurance program at least. The group just gets charged more as a whole.
We really should be punishing people for bad habits with higher individual insurance costs. Smoking and obesity should be prime targets. Have bad genes that make you fat? Too fucking bad, work harder fatty or pony up.