How can you have release notes when you have a piecemeal release which now deliberately hides what a specific update is for? Or when they pull a release and say "no, bad release, use the previous one"?
Microsoft has abdicated release engineering in favor of what is essentially rolling releases.
My guess is MS themselves haven't the slightest frigging idea of what any release actually contains, and they really don't give a damn if your PC works after the update or not ... as long as a statistically "good enough" percentage is shown to work with the mandatory bullshit telemetry they've installed so they can measure how shitty of a job they're doing.
Microsoft has decided people are beta testers, and not giving them much choice in the matter.
And I'm afraid for me that means I might take security updates, and pretty much ignore all the "important" and "recommended" ones ... because Microsoft is bloody well no longer being honest about what they're installing on our machines.
I like my Windows 8.1 box -- once I turned off all the Metro crap, installed Classic Desktop, and turned it into a useful computer again.
I have no interest in being part of their beta program for WIndows 10, or for that matter even running Windows 10.
But make no mistake about it, with Windows 10 Microsoft is flailing around like a lumbering beast trying to decide what it is, having everyone be the beta testers, and making random and arbitrary decisions about what software they will permit you to keep.
Microsoft has lost the plot, jumped the shark, and shat the bed on this. And they're doing this to us without really giving a damn about our opinions of it.
Release notes would imply some coherent strategy. So far, I don't think they have one of those they can articulate other than "screw you, we're updating your computer and don't give a fuck what you think".