We hear in the news everyday and experience within our own organizations the value of data. Data modelers are the ones responsible for coming up with a common business vocabulary representing the data, and building precise diagrams of the data as a prerequisite to building useful applications. Therefore, the data modeler is an extremely important role to organizations, and having the DMC shows your organization that data is in the right hands.
Also, having a DMC is objective proof you know data modeling to current and prospective employers. Certifications can also lead to higher salaries (in this study at least 20% higher).