Underlying systems are often large and Clients often have an interest in only a specific subset of the data. They do not need, or want, to be burdened with viewing portions of the Address Space for which they have no interest. To address this problem, OPC UA defines the concept of a View.
Views can be used to subset the complete Address Space for different uses. An example would be the exposure of plant information with an operation view, with a physical layout view, and an electrical interconnection view.
Simpler navigation; client only sees objects that are needed for a specific view.