Here's an experiment. Take your camera and look at something through the view finder. Zoom all the way in. Now zoom all the way out. Notice that, zoomed in, you can see many details of the area you are focused on, but when you zoom out, you can see a much larger area. This is a law of perception - Field of View and Level of Detail are inversely related, given the same data flow. When you increase your Field of View, you decrease your Level of Detail, and vice versa.
"Well, clash," you say, irritated at the irrelevancy of the previous paragraph, "What's a camera got to do with RPGs? Are you changing your blog subject now?"
Hear me out! That is just an easily demonstrable illustration of that general principle, which applies to anything, including RPGs. The more detail you put in, the smaller your field of view needs to be, or else you need to increase the amount of information - i.e. make the game longer. This applies to everything - systems as well as settings.
Generally, increasing detail gives you increased flavor, but there are things you can do to increase flavor without increasing size much. Painting in broad strokes while implying much more is one way. With this method, the reader supplies the missing detail, much as the viewer of the movie Jaws supplies the shark. Increasing detail in the system - which generally is much smaller in total size than the setting - while keeping the setting sketchy is another. With this method, interacting with the system supplies the missing setting flavor. A third way is to allow the users to generate the setting in whatever detail they like by supplying setting generation tools. This engages the group's/players' creative abilities in a rewarding manner.
Of course, you can always just write more on the setting...