> 1. Touchscreen computers are in the minority now, but I don't think they'll remain in the minority.
I'm not completely sure I agree. But as with most things in technology, reflecting on past design changes or evolution isn't always a good marker for what's in store for the future. For one thing, I can foresee typical desk positions as a contributing factor to shoulder strain when using a touch-style monitor for prolonged periods being a problem. Would it be useful for some things? Sure, but I don't see it as completely practical when the user essentially has to reach up and press the monitor all day for various tasks (industrial use cases might be worth researching here since so many of them rely on touch interfaces or similar, particularly in high tech factories, but most of these workers are not only standing but the buttons are quite large).
Remember, the same kids you mentioned who are growing up with touch devices have also been exposed, generally, to pointing devices in parallel for much of their lives. The mouse, as a pointing device, is going to take a ground breaking technological leap to kill--touch alone isn't going to accomplish this because the precision simply isn't there.
Realistically, I don't see it as backwards: I see it as practical.
> 2. Removing charms, for example, did nothing for desktop PCs.
(Disclaimer: I never used Windows 8 precisely because of these decisions. Likewise, I'm a Linux user. That probably tells you everything you need to know.)
Charms annoyed the hell out of me; rather, the fullscreen application of them annoyed the hell out of me. For one, defaulting to a fullscreen UI on a desktop absolutely breaks workflow for most people (myself included), it's visually jarring, and making something scroll horizontally in a desktop environment is not only inconsistent with the default behavior of most applications (also designed for a desktop environment) but it's almost painfully awkward to use with a mouse. I commend Microsoft for trying something new, but their current decisions to make Windows 10 more like a 7-8 hybrid are suggestive of a deeper truth: There's no business sense in alienating a substantial majority of your install base by imposing a UI that's both painful and intrusive to use for most desktop users.
To say nothing of the various hotspots enabled by default that were clearly intended to be used with swipe gestures. You could argue it's annoyance bred by lack of interest in learning a new UI (it's not), but when that same UI is intended for something that primarily uses touch interaction, shoehorning it into an environment where the primary interaction is through a pointing device, you're left with a disaster. Hence Windows 10, which I don't find all that bad.
Also, I should note that while tablet mode in Windows 10 still retains some of the smaller, more difficult-to-activate-via-touch items in the start screen, we're still discussing a preview version of an OS that isn't expected to be released until October. I expect that they'll further improve tablet mode for touch users.