I take exception to your comment:
"If you were to aggregate the R&D investment and resulting technologies coming from commercial software companies over the past 15 years, you would find the bulk of software innovation has come from commercially funded sources."
First, and most obvious, to measure "software innovation" using some basis of "R&D investment", commercial software will always NECESSARILY come out ahead. The Open Source community works on their own free time, tirelessly.
Second, I must question whether "innovation" can ever come from proprietary and closed sources. If no one else can benefit from the "source" of the innovation, there can be no true benefit to the community at large. There can be no cross fertilization, no criticism, no outside improvement. As far as Shared Source, it seems only possible to use it to assess the bugs in a system, as no one is permitted to make changes.
I would also ask, based on what "argument" is the Windows source code the "most valuable"?