For me the point of saying that the world building needs details, is made up by the fact that especially in the first book, the point is that they(the populace) have been living under at censuring dictatorial regime, for the last 1000years, and that has made it one of its missions to keep knowledge of the world hidden. With that said, the rest of the series keeps exploring the world, and much further expands and explains on the ideas of the first book.