Use Case: An instructor would like to use Announcments as the key communications vehicle for their class. For most announcements, the instructor wants to send an email, ascribed with high priority (such that, for instance, students cannot opt out of such email notifications via My Workspace - Preferences - Notifications). When creating a new announcement, the instructor must remember to set the Email Notification from the system-wide default 'None' to 'High Priority'. In this case, setting a site-specific preference for Email Notification default value in the Options view of the Announcement tool would be convenient.
(With that said, I very much appreciate the 'Notification setting' that's stored in the revision history for each announcement.)
This proposed solution mirrors similar behavior in the Email tool (sakai.mailsender) where its Options view displays site-specific preferences ascribed to new emails composed.