"It's questionable whether typing stuff, even just a few letters, should always be considered faster and/or more productive than using a mouse."
No, it isnt, but keep telling yourself that.
"Sometimes, especially on a laptop, it's a pain to keep shifting from mouse to keyboard and back."
Exactly why you should avoid shifting away from the keyboard in the first place as much as possible.
"Besides, since when is running a particular program the only thing you would ever want to do on a given operating system?"
Well, running one program or another is in fact the only thing you would ever do an any OS. That's the entire point to the shell, and all the other stuff that has to be loaded underneath it. Am I misunderstanding you?
"Windows 8 if filled with non-intuitive commands,"
Like every other computer OS that's ever been or ever will be invented, yes.
"and offers almost nothing of value in return for scaling its rather steep learning curve."
Yeah, that I have to mostly agree with you on. It DOES offer some value - there are some real performance improvements over 7, and I have to give MS kudos for that - that's several releases in a row where they have managed to reverse their historical trend to ever-increasing system requirements - every MS system up through Vista was more bloated than the last and they have actually been trimming and tightening a bit with Win7 and then again with 8.
But the Metro interface is painful and stupid. The only point to it is to drive people to Windows Store and Windows Phones and for that reason alone I would like to see Win8 die painfully and profitless. The average end-user sees that upfront and experiences pain as a result and hates it, while s/he in most cases never has any call to consider whether it's more responsive, more stable, and has more free memory than the same machine would have running Win7, so to them it's a completely negative experience.
To the technically adept user it's a much more positive experience though, because we tend to naturally avoid the interface stupidity and are more likely to be aware of the improvements.
(A little historical note, "Metro" actually started in the early 90s with the Chicago team, who did a mock-up and a useability study before scrapping the idea. It gets dusted back off now because end users are no longer their customers in any statistically significant sense, and their entire focus right now is on OEM sales, Windows Store, and trying to find some way to get people on Windows Phone. )