It doesn't help that many people seem to want Microsoft to be IBM. They loathe any attempt by Microsoft to build consumer-oriented products, or to move out of last decade's consumer direction and into the very different arena of mobile personal computing. They yell and scream (over the internet) until Microsoft finally caves in the spirit of "compromise".
Your reasonings are invalid, here's why:
1. Kicking your former customers in the * is no requirement to corner new markets.
The way they have tried to shove metro down the throats is as if they would have tried to make IE an success by not just bundling it, but by booting into fullscreen IE in Windows 98 with no obvious way to get out of it (except keyboard shortcuts), and if you wanted to launch programs you had to type them into the adress bar of Internet Explorer.
Such senseless brute-force tactics will only generate resentment! People who bought Windows PCs expect Windows, W8 just wasn't it (if you want to argue me with on that, you know I can type out a 10 pages post with ease on this issue...)
It's like buying the steak you always are buying and finding out it's made of soya and tastes like coffee, just because the vendor tries to make it big in vegan drinks. Not acceptable. Even if the customer wanted to buy vegan coffee later, he most likely won't chose THAT vendor again after that experience.
And what's with the all the other dick moves, like the completely non-controllable Windows Update in 10, hiding local accounts to ridiculous extends through deceptive tactics.. how does that help to bring in mobile customers? They will chose the automatic options freely anyway, but all this force brings nothing except grievances for the customers who are already on Windows.
Pretty much EVERYTHING they did in the past three-four years was antagonistic against their existing customers, this in turn generates negativity which affects all their line-up.
2. Their vision of "universality" is misguided AND WILL NOT WORK.
The start menu in Windows 10 sucks. Why does it suck? There's absolutely no reason for it to. Why can't they reconstruct the Windows 7 start menu? You get the old start menu, and if you press the maximize-button (tablet-mode) you land on the W8 screen. Problem solved for both user groups.
Freeeware authors do this in their spare time. Yet MS doesn't seem to be able to pull this off. All their "universal" approaches are hillariously bad and terrible, even though the fixes would be laughably simple in most cases. There's no excuse to produce something like Windows 8 or the botched start menu in 10 when hobbyists (classic shell) do better. Seriously, what's up? It seems to be driven by the desire to create an uniform look, but this could be achieved by colors and theming. Killing usability will always backfire.
Their "Universal Apps" will fail, that's my seer-prediction. And why will it fail? Because Microsoft themselves cannot create applications worth a damn with this approach. Take the calculator or the PDF reader in W10 with their huge buttons and out-of-place appearance. They look that way because these apps need to be run on tablets and desktops at the same time, and these form factors are just NOT the same, one will always get the shaft.
If they can't even tame a simple calculator, then every other app will be botched as well.
This problem happens because there are only two classes of devices in an "universal app": Phones and "PCs". PCs are lumped together with tablets. It would have been simple for the OS to detect tablets (touchscreen + no mouse attached = tablet) but instead of doing the clean separation, they lumped together two entirely different cases into one category (recipe for disaster). By going this way, "apps" will always be full of compromise and look bad on one of the form factors.
3. Shoving metro onto PCs will never work.
You just don't need "apps" on a PC, period. If you look at the apps on Android and iPhone, there are mostly three categories of apps: Website-gateways, mobile-only gimmicks and games.
Mobile-only gimmicks is stuff like barcode scanners, flashlights, augmented reality.. some of these don't even work on tablets that well, on a desktop or laptop they are completely useless.
Website-gateways: The full site on a full-featured browser on a large screen usually works better than these web-slices they put onto smartphones. There were born out of a neccessity due the screen size, not because they are that great.
So, on a PC you just need a browser for the mundane tasks smartphones need apps for (online-banking, buying tickets, light word processing), and for the heavy-duty tasks you have the vast library of powerful Windows applications. Metro/modern/Windows 8 style apps/Windows store apps/universal apps/Windows apps or whatever they are called now will probably never reach the functionality of these applications, given their full-compromise nature by design and their restrictions.
The other category is games, but PC users have Steam for that already. The library is vast, the brand well known and the games and their engines just too entrenched on win32. Especially the AAA engines.
Metro is just useless on the PC. Trying to brute-force their tablets by brute-forcing metro on the desktop was thus a plan just doomed to failure. It could never have worked.