Hi David,
Putting aside the question of whether or not Ansel coined the term "previsualization" rather than "visualization" (which to me is no big deal .. he got his point across either way), I don't see how visualization goes against the concept of "the negatiive as score", etc. Here's why . . .
As I previously mentioned in this thread, the idea of visualizing a final image before you even expose the photo is much akin to a composer humming a tune before he writes down its notes .... or, for that matter, a painter making a charcoal sketch on the canvas before makes the final painting.
Obliviously, the photographer's immediate task is creating a negative an intermediate step toward the final goal. However, a musical score is also an intermediate step, an just as a composer who writes a score must certainly imagine (even hear, in his head) how the music will sound in concert, the Zone System allows a photographer to already think in terms of the "performance" of the resulting photograph: that is, how it will look in it's ultimate use (on a wall, in a book, as a snapshot, etc.)
What's your thought on this?
Best,
Christopher