My pet theory is that this is because the dev
tools department at Microsoft is not a pure cost
centre with the sole task of improving the platform,
they have Visual Studio licenses to sell.
This is the single most baffling thing about Windows to me, and it always has been. Why insist on trying to sell Visual Studio licenses, instead of maximizing the amount of software written for your platform(s)?It doesn't even seem like they're acting in rational self-interest by doing that.
I suppose their rationale is that they give a lot of development tools away for free, and you only really have to pay for the really enterprise-y editions. I guess? Still dumb to me.