Mark, This is an interesting point. It certainly gives a new meaning to the phrase “the glory of God is intelligence” (the meaning of which is nearly always misconstrued by Mormons).

In the KFD:

But if I am right then I might be bold to say that God never did have power to create the spirit of man at all. He could not create himself–Intelligence exists upon a self existent principle–is a spirit from age to age & no creation about it.

I see this as Joseph Smith trying to explain revelation in words that just can’t express the understanding he was given. He’s trying to use the words “spirit”, “man”, “intelligences”, “creation”, and “God” to describe something that we have no words to describe.

Still, the concept that a “man” has other — essentially undefined — aspects is a useful concept. It leaves open the possibility that statements made about “man” may only apply to particular aspects of man at particular times and under particular circumstances. (And perhaps not all “man”)

Thus, man can both experience death as we know it and be immortal — a seeming contradiction.

But we’ve known since the beginning of the 20th Century that “before” and “after” are entirely physical attributes. There are places in our physical universe (event horizons of any black hole) where time might as well be described as running sideways. Time, space, matter, and energy are all intimately involved in each other’s existence, and we have no way of describing “a time before time was created”. Even the term “creation” carries the notion that there was a TIME when TIME did not exist and then a TIME when TIME existed.

Beings from within time like us can no more describe conditions of eternity than the blind can describe the sensation of seeing. You’re trapped trying to answer the senseless question, “What’s the difference between a duck?

As much as we all love to appeal to the 1828 Webster’s, I think many of the JS statements in question clearly use the word “intelligence” to mean “something that is intelligent” rather than “spirit.” Look at the quote in #79 (above) from the KFD:

The mind of man–the intelligent part is coequal with God himself

Here it is explicit that he is referring to the part of us that is intelligent. The part that thinks. He calls it “the mind” and then “the intelligent part” and then he goes on to refer to it as the spirit of man. But, what does our eternal mind consist of? Does his statement require that our spirit body existed from all eternity? No. Even if we took it that way, is there a distinction between spirit body and mind, or is mind an emergent property of a spirit brain, or what? We simply have no guidance from JS on how to answer that question. Thus, your dogmatic statement about what “is false” is stronger than the evidence you can marshal to back it up.

This does leave the tricky question, which JSJ may or may not have worked out, of what the Sonship of Jesus represents. JSJ would have held that we follow Jesus in broad terms, so that may provide a clue about where JSJ thought we came from.

There is no question that accepting the uncreated spirit model (I used to call it the “whole cloth model of spirits”) has far reaching theological implications. That is why I argued against it for so long. But I now am not so worried about those implications even if it leads to surprising places.

I am not usually a fan of hermeneutics, but in this case I see Joseph Smith using the word “spirit” to refer to a composition, and then various other statements referring to different parts of the composition. So, unless you already know what he is trying to say, it is almost unintelligible.

Also, Joseph was both a prophet and a man. A couple of times he uses phrases like “infer” and “in my estimation”. In those cases, he seems to be trying to reconcile his worldly experiences with revelation. I think too much weight is placed on those statements.

As to reasons why this is so important, the sermon itself gives several.