The upside to the Microsoft "monopoly" is that it provides an entity that can unilaterally introduce certain major changes in the way we compute. I'm thinking specifically about the pending introduction of Windows Future Storage which, beceause of the incredible market penetration and dominance of Windows, will have far greater impact than if a similar technology had been introduced by Apple or any of the Unix-like operating systems. I can name four journalling filesystems for the latter bunch off the top of my head and none has a markedly greater userbase than the others, meaning that application developers can not readily employ any advanced functionality over baseline without either massive replication of effort - once for each of the four - or supporting one or two to the exclusion of the rest.

The downside to the Microsoft monopoly is the probability that Microsoft will attempt to dictate how we compute, rather than respond to user needs. From trying to limit what software you may install and run to forcing you to upgrade/repurchase to unfairly exploiting its market position to make vendors of complementary products do its bidding - all of which it has done at various points in the past - it essentially gives Microsoft far too much sway and say over how we interact with our own data.

Ironically, the pro and the con are the exact same thing. The sole difference is whether Microsoft employs the ability in our interest or not.

Interesting. Your response very closely resembles what I wrote in my essay. :)