You make valid points regarding the psychology behind the purchase of computer platforms. But if what you say is true, then any strong-arm monoplistic practices by Microsoft should have been utterly gratuitous. After all, who chases after someone who is already running toward him anyway? Therefore, in seeking to explain the success and market dominance of Microsoft, I think you need to give more credit to its Draconian (and illegal) practices of the past (and present).
You lose me also when you say that unlike Gates, Jobs has failed to understand that ubiquity -- not quality -- is what will rule the world. The problem here is that you predicate this statement on the assumption that Gates and Jobs have shared the same goals. They haven't and they don't.
Make no mistake -- I'm sure Jobs would like to see significant gains in market share for Apple. But I see no evidence on his part of any aspiration for complete market dominance. It's one thing to want to be a major player; it's quite another thing to want to be the ONLY player. Jobs falls in the former camp while Gates falls in the latter.
I think what rings Jobs' bell is developing new technology and wowing the market with it. Of course he wants his products to be a success, and of course he wants to see healthy profits for Apple. And he's a tough CEO -- no question about it. But inside him beats the heart of someone who can still get excited over new technologies -- and I see no evidence of this from the cool-tempered Gates.
I differ with you also in respect to the idea that the market share of all non-Wintel platforms will continue to shrink. Notwithstanding the "buyer psychology" you cite, there will always be a place for a few other players in the industry. Indeed, while in some quarters Apple's market share might be decreasing slightly (even as its installed base is not), the market share of non-Wintel computers IN GENERAL is actually increasing or at least holding steady -- what with the prevalance of Linux. Besides, the very fact that these alternatives still survive in spite of the Microsoft-Intel monopoly is testimony to this.