If someone made quantified claims about "the number of minutes of life lost to smoking one cigarette" I would refuse to take them seriously: I would argue that the health risk from smoking is more complex than that and can't be reduced to such a linear calculation.
This talk about "the cost of a defect" has the same characteristics. I don't mean the above argument by analogy to be convincing in and of itself, and I've written more extensively about my thinking e.g. here: https://plus.google.com/u/1/+LaurentBossavit/posts/8tB2RQoHQ...
But it's a large topic that quite possibly deserve a book of its own.
As for the history of software engineering, it's pretty much the same - to do it properly would entail writing a book, pretty much, and I didn't want to do it on WP unless I could do it properly.
