There is, quite clearly, a difference in value between types of knowledge. Let us, for the sake of argument, divide knowledge between that which is known from personal experience and that which is known without personal experience. Which is considered to be more valuable?
Let me give an example to help make it clear. A recent news report told the story of a group of school principals who had objected to the draft national primary school curriculum on the grounds that it taught too much history and not enough numeracy and literacy. The draft, it was claimed, had been written by a panel comprised only of "academics" and no teachers. One person interviewed by the reporter had the caption "Education Expert" hovering across the bottom of the screen, under his name, and was expressing an opinion similar to that of the principals and different to that of the "academics."
So what is the difference between the principals, the education expert and the academics? The principals have knowledge derived from experience in the classroom and the principal's office. The academics and the expert did not get the luxury of an explanation as to their titles, but we can imply from the report something like this: academics have been to university and read many things and written many things about education, but have no actual experience; the expert is... someone who can be trusted to know the "real deal" of the situation? Who knows - as long as the expert isn't an academic. The perceived value of the academics' opinions is reduced, based on the origin of knowledge as impersonal. The perceived value of the principals' opinions is increased, also based on the origin of the knowledge. And the expert? Also considered to have valuable knowledge, but only by not being called an academic.
I have to conclude that the reporter (or the respective editor) believes that the public considers an academic to have no "real world" relevance, in deference to those who have "real world" experience. This decision is made based on public opinion; public opinion found through ratings research, etc. But why is it public opinion? What is it about the concept of theoretical knowledge that reduces its perceived value?
I suggest that it is because of several factors. First is the primacy of experience as a modern method of verification and research. Science and rationalism rule the methodological world, generating tangible results. Tangible results imply validity, and generate trust in the method. Furthermore, there is the notion of subjective truth (in a loose way); knowledge that is true for one, false for another, but still valid. Such truths are experienced and are personal. Whether we realise it or not, we give value to that kind of knowledge.
Secondly, there is a general mistrust of explicity authority and institutions. Anyone who claims to be an authority, without any demonstration of that authority, is immediately at a disadvantage. Any number of doctorates mean nothing, unless the audience has an experience with that person as a knowledgeable person. The audience needs to experience the knowledge contained within the doctorates, in order to validate them.
Thirdly, although probably not the final word on the matter, there is the problem of the difficulty of theoretical knowledge. It's hard to understand theory, and very few people engage with the task because of that difficulty. The knowledge is therefore out of reach, not understood and without understanding there is devaluation. A similar situation is found in studies of racism: a lack of cross-cultural understanding contributes to cultural bias and prejudice.
Now, in the interests of full disclosure and analytical impartiality, I must say that I am aware of my own inclination for theory and that this seems like a defense of theorists and academics. That's not my intent. What I want to bring out here, through the observation that there is a general prejudice against academic knowledge because it is not perceived to be grounded in experience, is that experiential knowledge is considered to be more valuable. Taking such a position limits the individual, isolating them from demonstrable fact, and exposing them to the risk of delusion and deceit. At one point in history, experience indicated that the world was flat, that the earth revolved around the sun. Without the theoretical knowledge, the wrong conclusions will be drawn from the data. The second point to reiterate is the manipulation of the general public through the careful selection of labels and tags. The "academic" is mistrusted as much as the "Marilyn Manson fan", or the "person of middle-Eastern appearance."
But of course, all this is theory and observation, generated from behind a desk by someone pursuing academic goals.