Edward O. Wilson and Steven Pinker are excellent science writers. Both are arguably better science writers than scientists. E.O. Wilson’s work on insects was really good, but his sociobiological ideas are less original than the ideas of e.g. Bill Hamilton or Bob Trivers (a talk by Trivers here). Steven Pinker’s ideas can be summarized as Chomsky plus Tooby & Cosmides; he stands on their shoulders but it it not clear that he sees a whole lot further than they did.
As writers both Wilson and Pinker are prolific, clear, readable, and mostly right. Their books are widely read. Those are great accomplishments.
The person who has done more than anybody else for building the market for science writing is John Brockman, who is a very successful literary agent. He correctly describes himself as an impresario. By creating hype and hoopla around a bunch of nerdish scientists he has promoted the public understanding of science and provided a real public service (see his Edge website, profile in The Guardian (pdf)).