Frankly, I think the last thing the government wants to do right now is discourage people from smoking. Cigarette taxes are one of their few remaining, dependable revenue streams.
That being said, smokers will smoke until they are sick of it -- either literally or figuratively. Is there a smoker in the whole U.S. who isn't already aware of the warnings those images depict (smoking is addictive, bad for children, causes lung disease, etc.)? Are there even that many remaining who didn't know those things before they started smoking?
Okay, if the scary pictures scare off a couple of kids from smoking, all fine and good. But if the government were serious about attacking smoking, they'd either just outlaw it, as they've done to other plants that people like to burn and inhale; or else they'd provide heavily-subsidized smoking cessation assistance. Inasmuch as they've done neither, I have no reason to suspect that they're all that interested in discouraging it. I think they care more about the tax revenue than anything else, quite frankly.
-Rich