Minor Prophets

Amos, Habbakuk, Haggai, Hosea, Joel, Jonah, Malachi, Micah, Nahum, Obadiah, Zechariah, Zephaniah. Christians refer to them as the Minor Prophets. Jews compile them into one book and call them The Twelve. The Major Prophets consist of Isaiah, Jeremiah, and Ezekiel to both Christians and Jews, and Christians also put Daniel in the that category. (Jews put Daniel in the Writings category.) Were the messages of the Minor Prophets less important to the Israelites? Did they just publish less material? Is there a reason to call them Minor other than the fact that their books are much shorter? What do we do with the many prophets of God mentioned in the Bible who never published a thing?