Now I, Chemish, write what few things I write, in the same book with my brother; for behold, I saw the last which he wrote, that he wrote it with his own hand; and he wrote it in the day that he delivered them unto me. And after this manner we keep the records, for it is according to the commandments of our fathers. And I make an end.Sounds like some high school essays I've read. But Chemish teaches us a valuable lesson: writing meaningful scripture is no easy task.
The flavor of the Book of Omni makes sense to me, and says something about where the Nephites were at that time in their history. They certainly needed the spiritual rejuvenation that would occur by fleeing, encountering the Mulekites, and having great leadership from Benjamin, Mosiah, and then Alma.
The different flavors of the books of the Book of Mormon, and the distinctive styles of its writers (e.g., the almost overly sensitive Jacob versus the straightforward military style of Mormon), all point to a book with complex authorship, an authentic ancient record spared for our time and made available through the power of God -- in spite of a human translator, human scribes, human printers, and further human editors along the way. Like the Bible, there have been some changes in the Book of Mormon, but they generally make a lot of sense and are hardly the cause for concern that the critics would have you believe.