Badger,
I tend to agree with you, though I feel a bit conflicted about it. If I were to trace a drawing from a projector or something of the sort, I would feel guilty, like I hadn't gotten a likeness by fair means or something. But really, that is kind of silly. I think it comes down to worrying what other people would think and the fact that non-artists have a certain inaccurate idea of what it is an artist does. They think it is something magical, like the gods touched you or something and you can just mysteriously do this thing that nobody else can do, the idea seemingly being that even the artist doesn't know how it is done, maybe that the artist is just a vehicle for something coming from God. Words like "talented", "gifted", "genius", "inspired", and so on all are evidence of this.
In reality, in at least some important respects, it always has been a very technical matter, and there is a method that can be taught. And how a likeness is captured is in fact comprehensible, even being somewhat of a science in many ways.
And at least as far as direct representational painting goes, even when not using optical devices to trace, the realists have long used very precise methods. The method taught at academic ateliers, for example, has long involved "sight size" drawing/painting, fixing your station point, or the location from which you make your observations, measuring with a brush handle, a knitting needle, or something of the sort, with the arm out straight at a repeatable distance, very carefully reproducing angles, distances, and so on, basically plotting all the important points and lines. Many have often even used plumb lines. And painters who don't obviously measure in a such a direct way are doing something similar mentally, still working out all of the spatial and color relationships like a surveyor.
But I think the art-appreciating public wants it to be something more magical than that. And when they buy a painting, they want to feel like they are participating in something otherworldly, something utterly mysterious, something that can never be codified or fully explained. Maybe unconsciously, they want to own a divine spark fallen from Heaven. And something like Tim's Vermeer, therefore, is deflating. Here is a guy who is what they might think of as a mere technician, a geek, who, using computers to help him reconstruct Vermeer's studio and an optical device to paint with, basically replicates what Vermeer did. He shows how the magic trick was done, removing all of the mystery, in fact forcefully demonstrating that it is not mysterious at all. With the aid of technology, Vermeer perhaps became a human camera, coldly recording the scene, no heart or soul necessary.
Still, in many artworks, I think there is evidence of something harder to pin down, and it often creeps in right where the work deviates from direct realism. Even in realist works, it is often to be found in those spirited and expressive flourishes of the artist's hand. But honestly, I don't see very much of that in Vermeer's work. I think that Vermeer might be a special case. Regardless, perhaps more important than exactly how the accurate drawing and color were achieved are the subject matter, the composition, the feeling conveyed by the overall picture that the artist arranged, and so on.
But then, would a well-shot photograph of the same scene be just as good? What makes a painting special? Is it just that it is hard to do and that it is labor intensive and these give an added perception of value? Or is there something more? And if so, just what is it?