When you use workflow rules to set the possible values of a choice list field, the field won't be empty when a user creates a new issue. The field will display the first choice in the list.
If, like Functional Area, the field is not a required field, this may become a problem. Over time, as users submit issues, you may end up with a large number of issues with the wrong functional area. For example, you might end up with a lot of documentation defects logged against the Admin Guide, just because it is the first choice in the list.
To avoid this problem, you can add an < Unspecified > choice to the Functional Area list, and then update the workflow rules to include < Unspecified > as a possible value. When a user creates a new issue, Functional Area will be set to < Unspecified >.