While you have been working with your model you add more and more specific attributes of a particular type to the project, making the list of the available attributes in a project longer. In the meantime making some changes in your model may result in having some attributes available on the active list but not used in the model. As a result of this you may end up with a very long list of attributes. It makes the list of your attributes not clear and messy.
Attributes Manager is a convenient tool to access lists of all attribute labels and to manage them quickly and efficiently improving your productivity.