Yea, the government wants everyone to be treated equally even though they aren't and basically take away choice for everyone because of a few.
If you want better health for everyone, the solution isn't to tax everyone that eats Big Macs, the solution should be to penalize those people who are at risk for over-eating Big Macs and reward those for working to be healthy. I don't want to pay a higher tax on a Big Mac because I'm not at risk, so I'm going to be against paying that tax. It's unfair.
And under the "tax everyone" and "subsidize the sick with the healthy" system we have, how does a company promote a prevention measure? It would have to work for everyone for it to be cost effective unless you identified those at risk, and by definition it can not. It would only work for those that needed it. Moreover, the people at risk have no incentive to do it on their own. If individual risk were evaluated and tied to insurance, they would have the $$ incentive to live healthier and reduce their premium much like safer driving reduces car insurance.