I think Microsoft knows this and I think they don't want to make Windows open-source for fear that they could create their own competitor.
It entices developers who might otherwise leave windows to stay. Why bother leaving windows when all your linux toolchain needs are available under Microsoft's comfy corporate roof.
Meanwhile, they've acquired one of the largest repositories of open source software in existence and now. make substantial profit from this.
Not that this is bad necessarily, but this 'oh look how benevolent and great Microsoft is now' twist all these stories get is just kind of a bit ridiculous as far as I'm concerned.
Microsoft's still a business concerned with trying to dominate on as many different fronts as it can. It may have changed up its strategy, but the goal hasn't changed. And, while they do seem to be doing some good, their whole underlying business strategy of 'have a presence on every computer everywhere' still remains strong.
Well of course. That's the essence of capitalism, it's strange to me that you're remarking on one of the most fundamental tenets as if it's interesting or otherwise noteworthy.
The fundamental tenet of capitalism is businesses exist to make money, otherwise they die and the shareholders have to bail out the company and employees, which is exactly why shareholders make so much money, as reward for the risk of investment (or -- in our current system -- the shareholders get bailed out while everyone else suffers the loss). Microsoft makes money by capturing market share and increasing vendor lock-in. The idea of companies doing "good" is outside the realm of market dynamics under capitalism, so it's alarming to think that any self-respecting neoliberal could assume that a company is inherently "good" or "bad".
"Embrace, Extend, and Extinguish" is something microsoft has been doing since the 1980s, and the 1990s leaked Halloween Memos show they've been aware of the threat since Linux's inception, I'm honestly surprised they took this long to start doing it with Linux, although the user experience in the last 5 years has become rather seamless, in my experience, so it's likely that it's only now that because of that, and Android, it's seen as a real threat.
Reminders are important - and for some, especially the young guns, your comment isn't a reminder.
The problem is all of the binary blobs they used in developing Windows (the zip library is a simple example) are licensed from third-parties that probably don't want their software open-sourced. The libraries would have to be reimplemented for the OS to be usable (not saying it wouldn't/shouldn't happen, it'd just be a hurdle).
Third party licenses, such as Adobe's font parsing, would need to get relicensed or rewritten to have a usable system.
You should listen to Bryan Cantrill's rant on Sun's disastrous attempt at opening up Solaris. This isn't an easy task.
Funny enough though that not changing your process to fit software but trying it the other way around is the reason most SAP integration projects fail.