I’m not sure we ever will be able to know conclusively exactly what Mormon left out of the Book of Mormon, so I stick with my personal impressions and attempts to parse what he included. It’s interesting to me that even a “faithful” interpretation of it as a historical record can be much more ambiguous than most assume.
I accept the Book of Mormon generally as the perception of two men (Mormon and Moroni) who abridged all the records of their time into one concise account. (the small plates of Nephi
It is said many times within the Book of Mormon itself that the original writers picked and chose only a few things to share (e.g., not a hundredth part), and Mormon and Moroni picked and chose only a few of those things - all dealing with one central theme: How the interaction of God with his people would be best presented to people of a much later day. That’s selective history to begin with; when you add the long practice of “likening these things unto ourselves” and Mormon’s “thus we see” commentary (and the fact that Moroni might have had up to 35 years in isolation to craft and hone his story), it is easy for me to see how the final product could read like “the good parts version” concept described in The Princess Bride. (How’s THAT for a comparison? Am I Mormon or what?)
In other words, I believe Mormon and Moroni recreated a spiritual history record, filtered through their ability to look back at the destruction of their people - which easily could have led to the romanticizing of certain narratives and the actual selection of some things over others. When a writer goes into a historical account with a specific agenda, what he produces OFTEN is closer to “historical fiction” than to “unbiased fact”.Do I believe the Book of Mormon is “inspired fiction” in the same way that the term commonly is understood? No; I don't. Do I believe it is “true history” in the sense that it is unbiased reporting of fact? No; I don't. Do I think it is historical in nature and the record of an actual people? Yes; I do. Do I think it is a freakishly awesome book? Yes, and that doesn't even begin to describe it's awesomeness. Do I think most members understand the full extent of what it really says and is? Not at all; I know I don't. Do I think there is so much packed into it that it startles me on a regular basis? Absolutely - without a question.