This isn't about skeuomorphic design or lack thereof. Take a look at the examples page, at things like button groups or button strips. They're grey rectangles, and the only way to tell that they're clickable buttons is if you mouse-over them. This is a problem on a touch device because there's no way to trigger that state.

In fact, each example group has a grey rectangle in the top-left corner that says "Example" and the distinguishing feature is that it uses a bolder font in a lighter shade of grey. But otherwise a user might think it's also a button. So I guess when you say it's got to be incorporated into a Metro-style design, you just really can't have any other colored rectangles on the page anywhere lest they be confused with input right?

I'm not saying this to be critical of the author. I think he/she did a fantastic job, and the buttons look really well done for Metro style.

> This isn't about skeuomorphic design or lack thereof

"They don't look like buttons" is a complaint about lack of skeumorphism. An extremely common and accepted case, but a case nonetheless.

Metro-like buttons do not look like 'real' buttons and, embedded in non-Metro content, don't look clickable. In a properly designed Metro UI they are unmistakably clickable and work fine in touch devices. Metro is still relatively new and takes some getting used to in the wild. But hey, there was a time when people complained about the lack of underlining in the text of button-looking clickable elements in web pages.

You are right also, in Metro a colored rectangle with a symbol and/or a short word is meant to be clickable. Non-clickable elements should look clearly different in content or in styling. That is fine.

Note: I'm not trying to defend Metro as 'better' or 'worse', only emphasize the fact that it's different.

I'd argue it's not so much about skeuomorphism as much as it is about affordance. They don't look like you can push them and interact with them, which means you need to be much more careful about the context and design language you use them in.

But that design language and how it is used to create context is what the Metro ("Modern"?) guidelines provide. There's a lot of stuff here for example: http://msdn.microsoft.com/en-US/library/windows/apps/hh46542...

They do look clickable when in context. Verbs such has "Delete" signal to me, regardless of how much gradient or border-radius an element has, that it is in fact a button. As do actionable icons like a trash can.

But affordances (such as bevelled buttons) are not the same as skeuomorphic design. Bevelling an area of the screen implies that something is pressable and hence aids the user. Covering iCal in a fake leather bitmap does not help the user. WP7/Metro seems to have taken a lot of tried and tested affordances away, but hasn't really replaced them with anything.

Bevelled buttons make a flat object appear to be three dimensional. It predates what we think of skeuomorphism today, but it's just a predecessor.

You're right of course, but if you take that to the extreme, styling a clickable action with a coloured square is skeumorphism too (it's still a button). The way I see it, the concept of a button has long since tracended into a metaphor in the visual language of UI. Where it used to mimic the physical world, it has since been reduced to a symbol. I think that most people would say that the beveling effect is part of this symbol. If that is the case, then Metro tries to redefine an established symbol. This isn't unique per se - languages evolve all the time, but it does explain why a lot of people might be confused of it.