Of course, Apple should know this: it seemingly created the "tablet" sector with the launch of the original iPad. And while there have been many Windows-based slates on the market for quite some time, Apple seemingly got the mixture right and hasn't looked back.
It took a lot of advancement in battery tech, better touch screens, and low power processors that had enough power to drive a tablet environment to get into a comfortable form factor. Apple was simply the first to realize that the technology was available and did a rather nice job of packaging it.
He also went on the criticize Windows 8 -- without actually naming the product -- for pulling all the leg weight of the PC market into the tablet space. "You wind up with something that's very similar to what tablets were 10 years ago," Cook said.
You don't get the tablets of 10 years ago even with Windows 7. The technology wasn't there to make the form factor of the current tablets 10 years ago. Also, if anything, Windows 8 seems more lightweight than Windows 7. Exactly what leg weight is it that he says is being carried over? Perhaps he's talking about the ability to run traditional PC programs on x86 Win 8 tablets. Seems like an advantage to me, but I can see where Apple would want to sell you another (tablet oriented) app to do the same thing.
"Apple doesn't try to smash the two together and we're not trying to do it ..."
Funny, that's exactly what I thought you were doing with the Phone and the Tablet. Sure they are both touch screen devices, but the form factors are still very different. That said, both Google and Apple proved it could be done.
"The use cases in technology stacks on phone and tablet are very different to desktop and laptop, as are the user expectations, and the types of things you do are also very different,"
I tend to see tablets as close to laptops than phones. Of course, this is probably because I find Asus' transformer series to be more functional/flexible than most and thus the most ideal tablets currently available. I find a keyboard is of great benefit when using a tablet as more than just a media consumption devices. A mouse doesn't hurt either (think precision work).
"... but in time there will be a seamless user experience across all the devices."
So the issue isn't the convergence of the UI, but rather the fact that MS is doing it abruptly rather than phasing it in over time?
Personally, I don't see the advantages of Windows 8 over Windows 7 on current desktops. However, it isn't necessarily inferior either. Once I get passed the learning curve, it seems more of a side step. The functionality is there. It's just different. However, different isn't necessarily better. To me, it is less attractive and I'm less proficient with it. For tablets, however, it is a definite step up in usability from their previous offerings. I'm really looking forward to a "transformer" style Windows 8 tablet that I can run some of my favorite software on.
The big question is going to be future PCs. It is my imagining that touchscreen monitors and all in one systems will get more popular due to the tablet boom. Microsoft seems to be in a good position to address this market with Windows 8. For a traditional PC setup, allowing for more customization of the UI would be beneficial. Metro UI doesn't necessarily need to go away, but a full screen of huge tiles isn't exactly efficient when using a precise pointer like a mouse. Even something as simple as adding a smaller list style view (think WP7 list) that leaves part of the the desktop visible would be of benefit. They could have it fold out (or back) to the right half of the screen when the windows button is pressed. An auto switch back to default Metro UI when undocked for tablets would also be nice. But I digress. Windows 8 may not be particularly targeted at the traditional desktop/laptop experience, but I wouldn't assume it will do as poorly as Vista either. Though I will go as far as to say it will do a lot better if touch screen devices catch on in PC environments.