"...we had obtained the records [Old Testament] which the Lord had commanded us, and searched them and found that they were desirable; yea, even of great worth unto us, insomuch that we could preserve the commandments of the Lord unto our children. Wherefore, it was wisdom in the Lord that we should carry them with us, as we journeyed in the wilderness towards the land of promise," 1 Nephi 5:21-22.
It strikes me that this is both literal and metaphorical. They needed scripture to help them remember God's path in the wilderness desert of the Middle East and beyond to the Americas. We need scripture to guide us along God's path, as we journey in the wilderness of the modern world toward the throne of God, our Promised Land.
"But he answered and said, It is written, Man shall not live by bread alone, but by every word that proceedeth out of the mouth of God," Matthew 4:4.
It is so easy to fall into false teachings if we don't immerse ourselves daily in God's Word. Scripture is desirable and of great worth, because it contains the plan of happiness. Scripture teachs how to be joyful during mortality and how to live so that we might one day live with God again hopefully with our ancestors and descendants beside us. Who could ask for more?