How much is too much?

Thomas More's Utopia is spectacularly detailed. The level of micromanagement in the conception of Utopian social, economic, political, and military life seems to border on the obsessive, down to specific tactics used in warfare. That is certainly a bonus, given our working definition for Utopian fiction, but such in-depth descriptions are tedious to read. A audience that becomes bored or irritated by a story is likely to put the book down or turn off the movie, rather than paying attention to the message. At what point should intricate world-building give way for the sake of holding the audience's attention?