To further explain our plight here... say you come in here and have a lot of notifications. Once you open the notifications they all get marked (unhighlighted). You may not have time t actually check each one right now, later when you return you may forget where you left off, and actually have more notifications.
It would be great to just be able to check the things off as we answer them, and later still have the unread ones still highlighted as "unread".