After another weekend of reading various theories about how the Book of Mormon came into existence---Spalding no, Spalding yes; Revelation versus Fraud; etc etc etc---I felt it was time to summarize my position on the matter.
However, on reflection it occurred to me that the disagreement was really higher up stream than that, and mostly driven by an analogy between Martin Luther and Joseph Smith Jr.
Fundamentally, I see the LDS position on the Old Testament as sketched for example by Ellis T. Rasmussen in the LDS Encyclopedia as untenable. I see the Old Testament as the founding document of the religion that Jesus of Nazareth who became the Christ himself practiced, and into which his movement was embedded historically.
Given the plurality of laws, narratives and words of wisdom that the Old Testament espouses, all of which require filtering from conceptual models that are external to the Old Testament, in order to be applicable to the present-day---such as a cosmopolitan, interracial, gender-sensitive stance---there seems to be little profit of going to that document rather than any other.
This holds especially true for the prophecies of the Old Testament, which I cannot interpret as metaphorically encoded announcements of a divine plan, but rather see as political speculations of the respective and often competing elites of the times of authoring in Palestine and Mesopotamia. (This stance is close to Spinoza's position, though updated to reflect present day scholarship in terms of literary criticism and biblical archaeology.)
When Martin Luther approached the reformation of the Catholic Church, he tried to replace the control of the Church hierarchy with the Bible as a document that he considered unassailable. This position can be explained historically, but it cannot be replicated for a present-day Protestantism that has undergone the transformations of Modernity.
Joseph Smith Jr's restoration attempt flounders on similar points, in that it assumes a biblical primitivism for the Old and New Testament, and critically for its prophetic parts, that cannot be sustained any more than the Lutheran sola scriptura. The problem is that for Smith Jr, this stance is intimately tied to the correctness of his revelatory document, the Book of Mormon. Since the Bible is not a document of divine revelation in the sense that Joseph Smith Jr assumed, neither is the Book of Mormon, however its contents was generated.
It is really not clear how to take a different stance, given the discrepancies between divine control and human freedom in the story of early Mormonism itself. Honestly, it boggles the mind that the Book of Mormon is the product of a divine mind that can give an accurate prediction of how the Reformation will play out hundreds of years before it took place yet is foiled in its revelatory attempts of translating the Golden Plates by the wiles of Martin Harris' wife. To support human freedom in the latter case and divine control in the former is truly confusing.