What role does popular science play in society?
Well, I've woken up this morning thinking about electromagnetic field theory and how this is extended to field theories in general. There is not rosy way of explaining it. Yet, there are numerous popular science books and documentaries, about physics in particular but most sciences in general, which put considerable effort into trying to get the general lay public (i.e. individuals not working as scientists - many of whom have a science background) to appreciate the achievements of modern physics. For example, when I was still pondering which direction my career would take, I recall watching numerous documentaries on string theory. Unfortunately, all they did was serve as a way to promote the individual scientists working on that branch of physics without advancing my understanding of what string theory is. To be honest, it was mildly annoying (to say the least) with all these analogies which are quite useless in explaning the actual science. The sad truth is that, with all the cute analogies, the general knowledge on science has no operational value. In other words, it doesn't matter how much popular science that one imbibes because it cannot be used to do anything practical. This is not to say that we cannot understand any explanations of the physical world using popular science. Rather, it is to say that popular science is all explanation with little predictive value.
What then is popular science (popsci) good for?
One, it's a mild form of intellectual entertainment. I would go so far as use the term edutainment: useful knowledge with some value compared to soap operas or that sort of jazz. But I don't think this is its main role.
I think the main function of popsci is its public relations (some would go so far as to say propaganda) value to sell the need for various benevolent entities (governments, foundations, philanthropists etc.) to bequeth large sums of money for scientific experiments that would otherwise be hard to fund. For example, the European Union tolerates the LHC with an eye watering cost and annual budget of about because of the promise of what it could achieve. In effect, popsci ensures that a large swathe of intellectuals are kept busy pursuing fruitful and fruitless ends when they would otherwise pose a social inconvenience applying that intellect to otherwise malodorous ends. And we're not talking tiny sums; these are substantial investments in the name of great intellectual leaps. Whether those pan out or not is not my job to judge. I just think it is useful to know that this is a major function of popsci: to justify otherwise questionable investments.
In short: popular science is a form of journalism. This is not to say that popular science is not done by scientist. Actually, the majority of popular science journalists are (former) scientists who have taken up to evangelising science. But let it not be confused with science.
Other's thoughts: