Fear is especially useful in safety or health directives -- hence the often graphic images used in ad campaigns against smoking through the fear of developing lung cancer or other respiratory illnesses. When the negative consequences of a particular action are especially dire, fear is a potent dissuader. When you want to encourage people to engage in activities that result in positive outcomes (lose weight, you'll feel better!), hope is highly successful. It comes down to what is stronger -- the "fear" of the consequences of an action or the "hope" of the positive outcome. In terms of politics, it might be illustrated with the following slogan "A vote for the opposition is a vote for higher taxes and less freedom" vs. "A vote for our candidate will bring new jobs to the area."
Hope can definitely be dangerous if what is being "sold" as a positive outcome is really going to be detrimental. Remember, though, what Frankl wrote in "Man's Search for Meaning" -- If you can find a "why" to live, you can stand most any "how."