In our organization Enterprise Manager is used by many groups within IT. This includes the DBA team, Identity Management, Systems Administration and Security. From a business perspective, it allows us to manage our Oracle environment with fewer resources. It has become a "one stop shop" for administrative jobs, proactive monitoring of our environment and performance tuning.
Our Identity Management team takes care of creating new users across our organization whether they be faculty, staff or students. We have tens of thousands of users so having the ability to view settings and create like is invaluable. Systems administrators notoriously use very few GUI tools. Enterprise Manager Cloud Control shows graphical representations of things like CPU and disk usage which is an easier way of reporting resource needs to upper management.
Our security team is constantly running jobs to check for vulnerabilities. Using this tool they can make sure that they are not negatively affecting performance.