Its somewhat strange to on the one hand argue that the OS should be super simple (so simple as to hide the hard drive from the user), and in the next breath describe changing a preference as trivial: its not, stuff like that is really confusing to precisely those non-computer people -- especially Finder preferences which is often confused with System Preferences or Finder's other preferences (known as "View Options").
The argument is not that Apple should not make things easy. It is that Apple is increasingly doing this in the laziest way possible as opposed to actually thinking about the problem. The hard drive is confusing? Oh just hide it by default and add a preference. Ugh. They used to hate preferences, now there's one for strange trivial stuff.
I realize this is flogging a dead horse, but the point is that the OS is super simple for novices/casual users, but is trivially adjustable for power users. It doesn't matter if those adjustments are confusing to non-computer people - that can be a good thing - but it's nice that with a bit of computer knowledge, you can essentially be running a solid Unix machine with a pretty, though not universally perfect, interface.
My point is that I don't think (from my own experience), that these things have necessarily been made any more understandable in OS X land by half-porting some of these iOS metaphors. My concern is precisely that the experience really has not gotten much easier for novices, but more convoluted by competing ideas of the way computers should work shoved together.
Let's look at the hard drive example in more detail. What did we lose by hiding the hard drive? Arguably the most important thing was access to Apps. This has been a critique of OS X for a while, that the main way to access Apps is this strange folder that lives in the hard drive. Perfectly fair thing to want to fix. Spotlight made it simpler to launch for pros, but you can't expect the primary way to launch an app to go from recognizing an icon to remembering the name and typing it into a textfield that appears when you click on the top right, especially if the goal is to move to a world where people buy LOTS of apps. So to remove the hard drive, you need another easy "visual" way of moving through your apps. What they chose to do was introduce the "application picker mode" to replicate the home screen of iOS.
But the problem is that this is NOT the home screen of OS X, and so the experience is jarring and scary vs. a safe place to return to. Perhaps had they done something bold and said, look, by default now this is what you look at, then maybe it would have been interesting. Instead it is literally a bolted on feature. In iOS, there is no question how to launch an app, you see them all in front of you. In OS X, you start with a strangely empty desktop and a few "blessed" apps in the dock, and you are supposed to divine that a chrome spaceship means "show me the rest of my apps" Or perhaps you are supposed to figure out that a five finger gesture does that.
I have not done extensive user studies of course (but then again, neither has Apple), but I have witnessed this feeling scary to people like my mother. They don't know how to get out of it and are afraid to touch anything. It is not the safe "home" of iOS, it is the exact opposite: bizarro desktop-is-blurred-out mode. Touching most things on the screen now leads to launching some application, and since OS X comes standard with a ton of apps you'll never use, the app they launch is probably a random app they've never heard of which results in me getting a phone call asking whether they should be scared because they launched Time Machine or Game Center or some other thing.
Again, my point is not that Apple is not worrying about novice users, its that these features feel exactly like a pro user lazily saying "fine they want iOS, here's iOS". Apple understood that desktop metaphors wouldn't necessarily work on a phone, that's why they took the time to think up new ones. It would be nice if they'd also realize that phone metaphors don't always work on the desktop. Or at least think these things through a little more before just dumping them in.
I 100% think there is a system that is 1000 times easier to comprehend for people and hides the hard drive in a way where the common user will never need or care for it. OS X is NOT that system.
Now that I think about it, perhaps the "the big empty desktop" should go away. We have a proper documents folder, so it shouldn't be a dumping ground for all kinds of junk, which is usually what happens.
I consider myself a power user, and I've trained myself to stop dumping shit onto the desktop. And now it's empty. After reading your post, I think it's a great idea for the desktop to be replaced by launchpad. Currently, I keep my applications folder in my dock (in non-stack form).
If they made Launchpad the desktop, and reduced the mouse travel between app icons (I don't know why there's so much space between them... Macs don't have touch screens), I'd be very pleased.
The argument is not that Apple should not make things easy. It is that Apple is increasingly doing this in the laziest way possible as opposed to actually thinking about the problem. The hard drive is confusing? Oh just hide it by default and add a preference. Ugh. They used to hate preferences, now there's one for strange trivial stuff.