Wouldn’t it great if we could just forget about making money, and about cost? Then we could concentrate entirely on making products that users love and enjoy. But really, that’s not the world we live in. Business owners (also called “stakeholders”) expect User Experience Designers to meet the needs of the business.

Thus, an additional notation to our definition of what exactly is a UX Designer must include the following: a synthesis between the needs of the stakeholders and the users. They should both get what they need out of the domain (product).

A wonderful book that helps define the role of User Experience Design is: About Face 3: The Essentials of Interaction Design, by Cooper, Reimann and Cronin.

Here's a link to that book on Amazon.