@pleonasm - As far as I'm concerned the main problem with this is not that they necessarily use fear as motivation. I think that is fairly inevitable.
It's that they skew results in order to really push that fear. I think that should be illegal. There are so many scientific studies that have been funded by companies with something to gain by particular results and there's no way for the average person to tell whether or not the results are trustworthy.
If a company that sells diet pills funds a study that happens to say that obesity is a killer and their pills work really well, can you really trust that result? Because there have been quite a few studies that show moderate obesity isn't actually a big killer. It's the stress from dieting that can kill.
But the guys who sell the diet pills have no reason to reveal that.
If they want to use fear to sell, then that's one thing. Sometimes money can buy security. But lying about it is basically evil.