In a book filled with manly men, mega-talented artists, and literary geniuses, young Pricey is the odd man out. He's simply a goofy and kindhearted young man—which makes his sad fate all the more heartbreaking.
In fact, we see Pricey's story as evidence of the sheer brutality of the West. After all, Pricey is beaten and crippled by a group of men who are trying to steal Oliver's property, as they likely saw this kindly Englishman as an easy target. This brutal attack leaves him with greatly reduced mental capacities, rendering him unable to enjoy his greatest passions, like reading (Susan claims that "he is an even greater reader than Frank") and admiring the picturesque countryside (4.4.33).
With no other choice, the Wards are forced to send Pricey back to his family in England—even though that family seems pretty hesitant to take care of him. The Wards would love to help (he's pretty much part of the family, after all), but they know that it's impossible in their current circumstances.
In the end, this heartbreaking tale shows just how nasty things can get in the West—and how helpless the early pioneers were in the face of such brutality.