Indeed we do read differently Morris. You enjoy it how you like, far be it from me to stifle that. But if you are going to make WAGs, stick to the established canon. Anything else is a waste of time.
Should we not care about the after-image of a person? I don't think our sympathy (assuming the reader is sympathetic) is wasted on a ghost. That is merely an assumption. As Jim points out, while ghosts start of as merely a shadow of the real thing, they can become something in their own right. That is quite powerful, I think. Indeed often the idea of a person is far stronger than the real thing, and exists long after they die in some cases. Do we care as much about the person, as the idea of the person? I never knew Martin Luther King, but the idea of him is what inspires me and many others. Do I need to care about him personally, rather than what he represents and has become? I'll leave that up to you.
You don't have to care why Jim writes anything, he himself has said he doesn't care if people don't agree or like what he write (although I imagine there are limits to this). His primary purpose may be money, but that is a big assumption about someone we don't know (I assume you don't know him personally, like most of us). But I have known a few authors, both successful and otherwise, and it isn't really ever about the money. It is about the love of craft, the joy of the job, the strength of doing what you love most and feel best at. I think Jim has even used Harry to express this often enough when he writes about how much Harry likes actually doing magic. Yes it is hard and frustrating and terrible too. But it is often also very rewarding. I would not be so quick to just assume Jim is mostly in it for the money. He wrote Dresden because no one else was writing the story he wanted to read - that's worth thinking about.
He hasn't merely put it up for sale - he has put it out for consumption, true enough. But he wrote it also for himself too. So it does matter what he writes. Now we as a fan base, as an audience, may interpret it how we choose. But it is not up to us to decide what is written and canon, and what is not. You don't get to repaint the Mona Lisa just because it doesn't suit you. You can think your own thoughts about it, have your own opinions, but the paint is dry now and should stay that way. We can always write our own novels if we like.
To answer your question, the ghost is a by product of the soul. That is quite clearly established. On occasion they can work in concert, but it is rare. Think of a cup of tea. The cup is the body, the water is the spirit, the tea bag is the mind etc. The soul is both the sum of those elements, and the idea of those elements. The cup of tea. The dregs at the bottom when the tea is finished is the ghost - a remnant of something much more real but contains the memory of what was. The soul moves on to What Comes Next, the body decomposes, and the ghost is created in that moment of death. Gasoline, for instance, was once a byproduct of oil refining which later became a valuable commodity - but wouldn't have existed without the refining in the first place. A ghost goes on and has use in it's own way, but did not come into existence without the presence of a soul. I hope that answers your question.
As for Mortimer being unable to sense him when Uriel shows up, well I think if Uriel had wanted him to look like a ghost and act like a ghost he gave him the option, but he never really was just that. When Uriel shows up he is finishing the job (the whole point of which was to help Harry understand that he killed himself, and the effect of his choices, and perhaps also hint at the greater struggle going on around him). If Uriel had wanted Mort to sense him, then Mort would have been able to sense him. It's almost Deus Ex Machina.
The Corpsetaker is different because he/she is a necromancer. I imagine using the powers of death magic might have some bearing on how your soul travels through the spectrum of death, not that it made much difference to him/her in the end. How this was possible is not yet known, and it likely won't be until Harry is forced to know more about necromancy I imagine, if we ever learn it at all. Although I don't see how the WOJ ever says it isn't possible to encapsulate a soul. A phylactery is a tool that does exactly that, which JK Rowling called a Horcrux.
Whilst one can be two, two can not be one. The ghost is a byproduct of a soul, which can work in concert in certain circumstances. Whether Sir Stuart is or isn't is a little ambiguous, but at this stage not very relevant to the story. Corpsetaker almost certainly was a soul, but may also have been in concert with his/her ghost, just like Harry.
On another note entirely - in Grave Peril Harry had this to say about ghosts.
I saw the ghosts the dead had left
behind settle the score.
Ch38, p229.
The ghosts
the dead had
left behind... The dead leave behind ghosts, but they themselves go on. A subtle but important difference. Which lines up perfectly with the WOJ and established canon...and this was 10 books before ghosts were significant and we learnt more about that world.
