Sociology graduate student Nathan Jurgenson, writing in Inside Higher Ed, makes the argument that academics must make their ideas available and accessible to the public. He maintains that they must try to communicate more widely in order to make more understandable and relevant to a wider range of people. I tend to agree with him, but not just because this can expand the influence of the putative experts.
I'm frequently called upon to review article and book manuscripts for journals and publishers, and I often wish that the writers would make their work understandable and relevant to a highly specific public: me. Writing is a reflection of thinking and when the writing is unclear, chances are that the thoughts behind the writing are unclear. Most of the articles and books in the social sciences (and, I think, in the humanities) are so clumsily written and badly argued that no one who isn't professionally obligated to read them would do so. Too often, when I can make sense of them, I find few real ideas lurking in the dense prose and statistical manipulations.
The problem with academic writing, I think, goes much deeper than its tendency to be a closed conversation in cloistered circles. The experts often really have nothing to say.