Excellent point, Puritan Sailor. That is why some arguments for cessationism are specious. They run something like this, "Why do we need anything other than the Bible? Isn't the Bible sufficient?"
The answer is for the same reasons that not all OT prophecy was inscripturated. As you note, "They could have just been addressing specific issues in their time."
The same thing is true in the post-apostolic period, as has been noted by Augustine, Calvin, Gillespie, Luther, et al.
Scott