Both Win 8.1 and Win 10 work perfectly fine with either touch or keyboard/mouse. Both OSes are far more usable with keyboard/mouse than touch, IMO. The use of apps is completely optional.
Not when parts of the OS are, in fact, Metro/Modern apps. You can avoid things like the Groove music app (I think that's what it is called) by installing third party solutions, but if you were happy with WMP, having to go find something else to do its job is annoying. If it were just that one thing, it would be relatively trivial, but it's not (as far as I know; I only used 10 for a few hours before I got fed up and went back to 7). They have some of the system settings done via "app" rather than natively, and I have read that eventually the entire control panel will be in an "app." You can download stuff (like media players) to minimize the "app" crapp, but you can't get away from it completely. This is by design, of course... shades of how MS embedded IE in Windows 98 and beyond so they could claim it was actually one integrated product, and leverage their OS dominance to gain a foothold in another market.
Then there's the design compromises made to put tablet/phone apps into a desktop OS. 8 and 10 no longer have Classic or Basic themes, supposedly because they don't play well with the "app" stuff (and MS is not willing to put in the effort to make it work). If you're one of the many people who can't stand white backgrounds, you'd better get used to using your PC with sunglasses on, because the ability to change your colors in the "classic" way is no longer there.
The same "it doesn't play well with apps" reason is supposed to be behind the elimination of the Aero glass themes that a lot of people liked (and that was a major feature of Vista and 7). Since 8, we just get dull, flat UI with oversize (touch friendly on small screens) buttons (and retina-searingly white backgrounds), because that's what works with tablets and phones.
Microsoft wants us to run phone apps on our PCs, and they want to run the same OS on phones, tablets, and desktops, even though they're different devices with different needs. Even Apple (not a company I laud very often) gets this! But then, they HAVE an established phone app market, so they don't need to force people into their "ecosystem" the way MS thinks it has to.
The only feature in 10 I am interested in (besides more years of updates) at all is DirectX 12. The rest of it (Cortana, Action Center, Windows Store and anything else 'apps', OneDrive integration, Xbox integration, tablet features, Edge, Virtual Desktop, etc.), not only don't appeal to me, but are all things I would actively seek to uninstall, if that were possible. The new start menu is only good by comparison to Windows 8; it still isn't good enough (although Classic Shell, which I currently use with 7 to bring back the Classic menu, takes care of that). Tiles are something I walk on, not click on.
If I could get 10 with the UI as close as possible to Windows 2000, that would be ideal. That'd be even better than 7 as it is now! Win 2000 UI with 10 (less the features in the preceding paragraph). That I could go for. Just as an option, of course; I know not everyone agrees (though a lot do).
I'm not completely giving up on ever going to 10. In the five years before Windows 7 updates are stopped, there will be a lot of changes, not to mention third-party extensions like Classic Shell. I remember how despised Vista was on release, but it evolved into a pretty good OS-- and the much-loved 7 is just a slight evolution of Vista.
I tend to overuse parentheticals, I know. I'm too tired to revise the post, though, so I'll just document it and call it a feature.
