Very interesting. That reminds me very much of the Ice Age exhibition and lecture I went to at the British Museum, particularly the massive and wafer thin spearhead which you may recall too Moss? The curator was talking about symmetry in the lecture, it's something that our brains find pleasing isn't it. Your article says " they were more symmetrical, more finished and made with more expertise than was needed for the job." (Could it not be though, that it IS needed for the job to some extent? It's not much good having a totally wonky arrowhead or axe, is it really going to be as good at the job?) And if you're not in a terrible hurry, and you've got the skills, you'll want to produce something decent looking for your own satisfaction I'd have thought. Form and function but with a bit of human psychology and instinctive appreciation of well crafted, well balanced, easy on the eye object too? Also then you get some status, and the object gets some status. And as with that big spearhead, it becomes more of a symbolic object, not something that you'd use, because you've actually made it too flimsy to use. It's become a beautiful object in itself, a piece of art I suppose.

'Form and function but with a bit of human psychology and instinctive appreciation of well crafted, well balanced, easy on the eye object too?'
Does the eye instinctively crave beauty? I expect the answer is yes what the first hunters saw was the bulk of the bear, the graceful action of horses and lions moving across the canvas of the landscape and captured it thousands of years ago on the walls of the cave, probably not having a word for beauty....
Symmetry I believe is captured by the structure of the cellular nature of the eye, we are after all the result of a complex melding of thousands of cells...

Symmetry is certainly the key word isn’t it. Symmetry in the human body (especially the face) is fundamental to our appreciation of beauty; they were actually talking about that on the radio yesterday, saying that beautiful people were more likely to earn a higher salary. But why would symmetry in the human body be important? Could it be that asymmetry (in the extreme) was linked to deformity and illness... although interestingly people with deformities seem to have been treated with respect in some early cultures.
And is it reasonable to conclude that asymmetry in a hand tool might cause it to be less functional...