Anton Philidor is another one of those people I've seen around ZDNet for a long time. We tend to agree on many things, but we often disagree on details. I compare it to the difference between Irish English and Jamaican English (and I'll leave it to you to decide who has to put "Rasta Man" in front of his name).
You argue that reducing the amount of proprietary software denied entry to the brave new world of free software improves the result. You're right. Now just consider the result of not excluding proprietary software at all. Even better, no?!
...the main problem is not to find a defensible amount of open source software in the entire software ecosystem, it's whether open source software is defensible at all.
Anton makes an interesting point, one that has a certain resonance with things I've discussed in the past. The voluntary nature of open source doesn't lend itself as readily to consumer-oriented technology as the proprietary model, which uses financial incentives to orient developers towards the needs and wants of non-technical users. Financial incentives motivate more people to innovate, as not everyone considers the acclamation of geeks satisfactory compensation. The links with real-world customers is an advantage proprietary companies have over open source developers, and the revenue generated from sale of software drives the R&D necessary to tease out ways to apply new technology to satisfy those customers' needs.
On the other hand (and this is where Anton and I differ), I also see merit in the existence of an "intellectual commons" that can bootstrap new technology initiatives at little cost. I've made frequent use of open source products in past projects. I tend to favor BSD-style licenses, as that leaves me free to make changes which are kept secret, but I've been know to use GPLed code if I know I won't need to change anything. This saves me money, and accelerates the development process, particularly in realms that are already well understood or where "extreme customization" (versus "plugin customization" through well-defined extensibility APIs) is a requirement.
I seek a "golden mean" between the incentive power of financial returns and an intellectual commons. I think that both open source and proprietary software enhance a software economy. The trick is finding a mix that leads to maximum economic advantage. Admittedly, I think that the proper balance involves a lot more proprietary software than Eric Raymond would like (a fact I noted somewhere in my series on Raymond's "The Magic Cauldron"), but neither of us think that "all open source" or "all proprietary software" is a desirable outcome.
Balance is most undermined by those who adhere to philosophies espoused by the Free Software Foundation, and in particular, Richard Stallman. There is simply no need to create a world completely free of proprietary software. Such a world would be lobotomized (as I've noted before, most innovation necessarily comes from companies who endeavor to satisfy the needs of non-technical customers), and would lack the dynamism of a software economy that harvests the productive power of those who wish to extend the commons and those who wish to own a Porsche Boxster.
I think a more balanced world would exist if the open source community would listen to some of the points I made in my Competing with the Microsoft ecosystem post. It would cause Microsoft to further its moves towards open source out of competitive necessity, a reciprocal reaction that would match the moves towards proprietary software made by the open source community.
But I would say that, wouldn't I?