Personal experience would indicate that a lot of people hated Windows 8, not just because it took something they were familiar with and threw the biggest curveball at it possible, but because they actively made the UI/UX significantly more difficult to use.

For me the icing on the cake was segregating different apps between "tablet mode" and "desktop mode," where the former would take up the entire screen with no reasonable way to multitask between programs. Not only that but how many apps had (and even still have) both a UWP and standard implementation, from my experience that just confused users as to which they were supposed to use. Heck even today we still have the Settings app and the Control Panel (which is increasingly difficult to access I might add), both with various controls and settings only found in one but not the other.

IMO Windows 10 (sans tracking and forced pre/auto-installing apps) is what Windows 8 should have been from the beginning. Many beneficial changes under the hood, and minor UI changes that don't entirely change the workflow of the OS, but instead augment it for a better experience for both regular and power users. Somehow we've eclipsed the 5-year mark since its release, yet Windows 10 still feels incomplete. Not even just that, but they manage to make it feel even less finished with every new update.

I think the biggest change that killed 8 was the lack of the start menu. Having to go to the start screen - pulling you away from your entire desktop just to launch an app - was awful. I know Win 8.1 got it back, but for the time between 8 and 8.1 Classic Shell was almost necessary to use Windows 8. All that for no discernible benefit over using 7.

Although I find 8.1 still better than 10. Some of its preinstalled apps and UI were just weird, but at least it wasn't anti-user by design. Both are a clear downgrade to Windows 7 though.

Windows 8 is fine, _if_ you actually know how to use Windows. (Protip: Win-D takes you to the desktop from the app grid.) I would go so far as to say it's good, if you're using a touchscreen or tablet; the live tiles were useful.

Always amused me that the OS X Launchpad is also a ugly grid of huge app icons that takes up the entire screen, just like the Windows 8 start screen, yet nobody says a word about that.

Launchpad is simple to make work. I don't use Mac, but I can use Launchpad.

I do use Windows, in as much as I have to for work, and I still can't make Win8's launcher work.

Edit: Wrong version of Windows.

8 was great on the intended devices. I used it on an asus transformer tablet/laptop and it worked really well. W10 was a step down for that machine because they dialed back the tablet UI.