At the moment, the "default sudo roles" are used during user creation / editing to automatically add that user to the list of sudoers if the account has one of the default sudo roles.

However, when users are added to the list of sudoers - either through the sudo admin page or the user admin page - they are not given any sudo roles by default. It seems like it would be more intuitive to add the default sudo roles to users when they become sudoers, either on the sudo administration page or on the user admin page.