Just blogged a post on that very subject at the End of Journalism site – more optimistic than it sounds. You can read it here, but here’s an excerpt:

[D]o we need journalism to inform people’s limited choices? In the 1950s, an economist called Anthony Downs argued that the democratic system did not incentivize voters to become informed. His position? Because an individual vote is so valueless, people who try to become well informed about politics must be doing so either for instrumentally irrational reasons, such as perceived civic duty; or because they are ignorant of the odds of their votes making a difference, meaning that they cannot have rationally weighed those odds against the costs of being well informed. (The corollary, of course, is that elites like political information because they see ways of influencing the political process beyond the ballot box.)