Enhance user experience, unburden sysadmins
Allow users to stick with one set of credentials for the different personas they take on. Rather than having them remember a username and password for each role they take on, let them use the same credentials and apply Single Sign-on between the different roles. Let them use a self-service portal to define the attributes for their different personas. Make onboarding and offloading easier and simplify life for your administrators who no longer have to deal with a spaghetti of multiple accounts for the same individual.