john f posted on the Canonization of Kitsch earlier this week, discussing “the way Mormon art invents, and then canonizes, certain images” – in the case of that post, the repetition of elements of Arnold Friberg’s Book of Mormon illustrations in more recent depictions.
While I have little to offer about the how and why such apparent canonization occurs, I can offer an illustration showing how quickly it happens:
The same morning john f posted about canonization, I posted some paintings by C.C.A. Christensen illustrating George Reynolds’s stories on lessons from the life of Nephi in the 1891 Juvenile Instructor.
The same year those images appeared in the magazine, Susa Young Gates prepared a “dialogue” or short play for the teenage girls in her Sunday School class to perform. I can’t overemphasize how seriously she took this assignment:
Believing that “The Book of Mormon is as little read and understood by our young people as if it were printed in a strange language,”  she wanted to “create a vivid interest in that divine work” by dramatizing a scene from the Book of Mormon.
She wanted to stay true to scripture, using “as nearly as possible the exact [words] represented in the sacred history. And while “there were one or two characters introduced,” she insisted that “a careful comparison of the … dialogue and the story as abridged by Mormon will prove that I have taken the smallest liberty possible with the sacred context.”
No horseplay among her girls was allowed during the production of their play. “I was present at every rehearsal and enforced a quiet and dignified spirit, allowing nothing to be said or done which would turn our efforts into ridicule. We were dealing with a sacred theme, and each one was instructed to strive for the blessing of success and peace upon our efforts.”
Susa’s concern for reverence in connection with this dialogue is so great that she has an actress break character in the midst of the action and turn to address the audience: “We ask these, our brothers and sisters and friends who are here to witness our efforts, that they will listen kindly to us, and not laugh or make fun of us if we do not succeed very well, for we are only girls and this is our first effort.” 
So, you see that Susa had every intention of treating this presentation as a sacred offering: The text was scriptural, the characters as much as possible were drawn from scripture, the cast prepared it in reverence, the audience was asked to receive it in the same spirit.
And the costumes? Well, they were to represent ancient Lamanite dress as literally as possible, too – to be as scripturally accurate as everything else. In describing the play’s staging, Susa reports how this was done:
Rose remains on the stage while the others go out to arrange their costumes to present as nearly as possible the costumes worn by the Lamanites as shown in the pictures published in the Juvenile Instructor.
Less than six months. That’s all it took for those images to be canonized to the point of being models for other artworks. Less than six months.
You can evaluate their success in duplicating Christensen’s robes – in canonizing the images he had created – by studying this photograph of Susa’s cast:
The text of the dialogue is posted separately here: Dialogue from the Book of Mormon.
 Susa very quickly retracted this statement, claiming to have heard from other teachers that the Book of Mormon was being read and understood by their classes, and that the situation wasn’t nearly as dire as Susa had pictured it.]
 Before anyone imagines that Susa was denigrating the efforts of girls because boys could have done it better, don’t. Susa’s whole career evinces respect and concern for “her girls”; she means here only that the actresses are young – girls rather than women.