I don't know how Metro looks lately, but when I tested a WinMo 7, the interface gave no clues of what elements are clickable and what elements aren't. So I ended up clicking like an idiot on images and on text, which sometimes triggered a click and sometimes it didn't, depending on how static or not the element was.

You can see this mistake in some Android/iOS apps that come with their own custom designs. For instance Twitter on iOS is friendly and all, but after expanding a tweet, to view the full profile of that user, you have to click on that profile's image, while the profile's name is NOT clickable. I always make the effort of going through "what the hell do I click on? every single time I want to view a profile.

So if this still happens in Metro, with the UI giving no visual clues as to what elements can be touched/clicked or not, then your argument is not really valid, being a poor rationalization. In the real world things that can be acted upon either provide audio, visual or tactile clues (or all of them at once).

Also, I agree that the design in Android Jelly Bean tends towards the same kind of flat look. It looks indeed nicer, but it's not as radical. In general, buttons are still buttons, with the exception of things that are designed to be clicked as an after-thought (e.g. the clock widget's primary function is showing the clock, but it opens the dialog for setting an alarm if you touch it, but that's not the only way of setting an alarm, being just a convenient shortcut). There are some annoyances too, like the phone pad for dialing numbers, which just shows some white numbers on a dark background, something that's annoying me greatly.

Looking at the link http://www.riagenic.com/archives/487 it shows they contrasted Metro with gaudy and awful chrome. I think it is a bit of a straw man in this case. Metro just took a idea and implemented the extreme of it. And extremes don't always work well there needs to be some compromise. This doesn't have to be all 0 or all 1 (all gaudy horrible chrome or completely flat polygons filled with color).

"authentically digital" -- I am all for it except that most people already have some baggage or notions of how interfaces work (both in real world and digital). It also happens that those in digital world mimic those in the real world (buttons have shadows for ex) or some conventions have stuck that have been randomly chosen initially (links are underlined).

Now maybe it is a noble goal to re-educate the user and I can see that. I remember hating Ubuntu's Unity. Now I like. It has re-educated me. But I also happened to like other aspects of Ubuntu and didn't want to switch to an alternative that why I stuck with it. But it seems a lot of people did and a lot of people will also do that to Windows.

The only aspect of W.I.M.P. that exists in iOS is I: icons.