As the person responsible for the original concept and a significant amount of the design work for Longhorn (which became Windows Vista), including Aero Glass, if anyone should have a problem with Metro it's me; but I don't.
The initial premise for Glass (as it was called back then, the Aero UX sprung up around the Glass model) was not - as most people believe - to provide eye candy for the end user. Instead, it was an attempt to pull the window chrome away from the content and make it as unobtrusive as possible. The whole point of the glass effect itself was to allow the end user to make better use of their screen real-estate by allowing them to see content beneath the active window.
The first concepts did exactly that - completely transparent window borders with floating titlebar controls, however, this proved distracting to the end user as when a window behind had a lot of text or otherwise "busy" content, the user had to fight to recognise the window caption. It was then that we decided to apply a blur filter to the surface beneath, still allowing recognition of the content beneath but without being distracting to the user. Many, many trials were done to ascertain the appropriate amount of blur, incidentally. Desktop compositing and the DWM window manager were born out of a desire to make this as smooth an experience for the end user. Things like Aero Peek and hover thumbnails were also designed to fit this goal of making the chrome less obtrusive.
Some of my other concepts promoted a VERY different approach to the user experience, much more in line with what is seen today in Windows 8. In fact, the premise for the shift in the desktop paradigm goes back as far as the early Blackcomb concepts first demoed by the MSN services division in 1999; it has ALWAYS been felt that the desktop itself is a rather clunky way of providing content to the end user, which is - after all - the purpose of computing devices, be they traditional desktops, laptops, phones, or even set-top boxes. Windowing systems were designed to allow users to work on multiple pieces of data in quick succession, and yet over the years usability studies have found that users rarely manipulate more than 2 documents simultaneously.
A radical shift away from the desktop metaphor WAS considered for Longhorn, but rejected for numerous reasons; primarily due to the scale of the undertaking that was already planned for Longhorn. Various features got dropped over the course of the development - NOT the ones that were complained about by the public and the media at the time - but other technologies first proposed in Cairo and later carried forward to Windows 7 - and the focus slowly shifted towards the HAL, networking and the Aero UX, luckily for myself.
One of the other reasons for keeping the traditional desktop paradigm was Mac OS X. There were rumours that Apple would be making the switch to x86 and there was always a possibility that they would open OS X up to non-Apple hardware, in either a full or limited capacity. It was felt - most notably by Jim Allchin - that the familiarity of the Windows interface would offer people a strong incentive to upgrade to Vista, rather than exploring alternatives. Linux has never been considered a credible threat due to its inaccessibility to the average user, but OS X already had a niche - but highly vocal - following and was well-known by the public. The possibility of it being available as a competitor, which opening the OS up to generic hardware would have started, was a compelling reason to keep the familiar experience for those afraid of change.
Now, however, it's become clear that both OS X and Linux have been unable to provide a credible alternative to the general public, and so the plans for a content-centric interface were finally put into place. While some have suggested that Windows 8's interface is "touch-only" or "based on Windows Phone 7", that couldn't be further from the truth. Windows Phone 7 was instead a pilot program - in a relatively low risk sector - for the designs originally suggested for Blackcomb, which have now found their way into Windows 8. At the time, touch interfaces hadn't even been conceived of - remember, back then touch sensitive screens were Resistive nasties that required at best a stylus, or at worst jabbing at them hard with a finger or pen.
The fact is that Metro just happened to be easily accessible for touch devices, and that has been touted as one of its benefits; it is NOT, and never has been, the original aim of the design. The aim of the design is exactly the same as Aero was - to take the chrome away from the content, and allow the user to focus on what they're doing rather than unnecessary clutter. A perfect example of this is internet Explorer on Metro; in its default state, all you see is a webpage; chrome CAN be pulled up if the user requires, but is otherwise absent. The majority of Metro applications are like this - in fact it's part of the Metro UX specifications.
This has always been the way that computing has been going; customisation features have subtly been taken out of each successive version of Windows, as users have - on the whole - moved on from eye candy and instead focus on productivity. This isn't specific to the software sector; even social networking has experienced this shift - from the cluttered, flashing, marquee-laden MySpace profiles of 2003 to the clean, customization-free Facebook profiles of today.
Personally, I see Metro as a good thing; it allows me to do my work without distraction, and I'm just disappointed that I wasn't the one who did the design work for it this time around.