To decide on relative importance requires familiarity with the scene that the model describes and a keen sense of the user's purpose. If you don't perceive what's important to the user and what's not, then you easily overwhelm the user interface with irrelevant detail or omit something vital. Lastly, there is Occam's Razor. If you develop an Object Model , the similarities are expressed by placing similar objects in similar classes. The differences are expressed either by subclassing or by inventing properties that enable one to discriminate different types of object.
Object models afford no easy way to express relative importance.
That's why you can't see the wood for the trees when you look at a Java package. But object models do have a great way to apply Occam's Razor. You simply omit from the model unnecessary classes, methods and properties. The designers of Java packages have yet to discover Occam. 1 Applies to Project 2 3.