Well, if there ever was a place where low-noise graphics made sense, it must be Visio. Metro must be about a higher signal-to-noise ratio -- making it faster to understand what you see and therefore making you more (to use a marketing term) productive. Diagrams should be a perfect fit for that.
I don't think Metro has to mean lifeless or bland, in fact one of the phrases used to describe it is "fast and fluid" - but it surely can be implemented in a way that makes it feel boring and uninteresting.
Google Chrome was also marketed on its simple UI. The UI was supposed to get as much out of the way as possible so you could focus on the content you were browsing (which makes its name ironic; surely on purpose but ironic still). The smaller the device, the more sense that makes but in any event, irrelevant detail never helps productivity.
It's kind of a balance; you probably don't want the chrome to be so sterile as to impact the overall UX negatively but on the other hand you don't necessarily want the Apple-way of super-detailed 3D chrome either because that has a lot of irrelevant detail; it looks beautiful though. I think one place where the UX is too sterile or boring (for my taste) is the new start screen.