I think Fowler was just reaching for a stick to beat the metric he was deconstructing - "look Joe writes only 10K lines but makes ten times the profit - that means LoC is not a good metric."
However I do think that (free) market success is a reasonable measure of value / worth - backed up by my favourite quote for which I can find no author:
"Many books are unfairly forgotten, but none are unfairly remembered."
Measuring value (profit) isn't going to be a reliable indicator of how well something was engineered. There's too many badly engineered products that make tons of money, and too many brilliantly engineered products that are commercial flops. So many other elements are involved -- finding the right audience, marketing correctly to them, luck, etc.
