Allowing a 'Role' to be entered in the 'Watcher' field in an issue would enable certain workflows that are typical in construction. If there is a group of people who are responsible for collecting, reviewing, tracking, and approving inspections, they could be collectively defined as the "Inspection Team". If issues with inspections are entered into the "Issues" workspace, then these people can be added as watchers quickly, instead of separately. And communication in the chat box can also use the "Role" name to communicate about the issue.
Allowing a 'Role' definition is already possible in the 'Assigned to" field. And in the 'Comments' field. It makes sense it should be allowed in the 'Watcher' field as well.
