When I joined the LDS Church, my initial understanding of the Pearl of Great Price was that it was a hodgepodge of random, “left over” little scriptures that got stuffed in the back. It wasn’t until later that I read from Hugh Nibley about how it was a collection of restored records from the major dispensations.
Look up “dispensation” in the LDS Bible Dictionary and you get this: “A dispensation of the gospel is a period of time in which the Lord has at least one authorized servant on the earth who bears the holy priesthood and the keys….The Bible suggests at least one dispensation identified with Adam, another with Enoch, another with Noah, and so on with Abraham, Moses, and Jesus with his apostles in the meridian of time…. the final dispensation…began with the revelation of the gospel to Joseph Smith.” Though other prophets began the work of bringing God’s truth back into the world again in their own times, these seven men are typically identified as the leaders of the seven major dispensations of Earth’s history (roughly equivalent to the seven seals in the Book of Revelation). Certainly Jesus Christ is not “just another prophet,” like the other six, but did establish his Church in his day, as they also did.
Looking at the Pearl of Great Price through that lens, we see that it is a record of the initital calling and/or early ministry of Adam (Moses chapters 3-5), Enoch (Moses 6-7), Noah (Moses 8), Abraham (Book of Abraham), Moses (Moses chapter 1), Jesus Christ (Joseph Smith–Matthew), and Joseph Smith (Joseph Smith–History). Not only does this give the “hodgepodge” Pearl of Great Price a coherent structure, it helps us see the regular, balanced nature of God’s work among mankind throughout history.
To further illustrate the power of the Pearl of Great Price (and thus explain the appropriateness of the title), consider the Church’s student manual Doctrines of the Gospel. Its appendix lists all of the scriptural citations used in the text to illustrate the principles considered. Though the Pearl of Great Price, at only 61 pages, constitutes less than 3% of the total body of scripture in the Standard Works, references to it add up to nearly 10% of all verses used in Doctrines of the Gospel.