metro is designed for casual users and their mobile devices, which represent the largest and still growing segment of the computing market. can't blame ms for catering to that. i see the writing on the wall; windows is not going to get better for us power users. this is why i'm making an earnest effort to switch to linux now. so far so good.
If anything, the Modern side gives options in addition to the desktop, on the go, in one device footprint. Something sorely missing up till now in the market.
I would agree, if Windows 8 did not have the desktop space period and it is SOLELY about that RT version.
But since it does, and functions very much like 7 and a bit better, I do not see any writing on the wall that this is going away. Hell, if you want some solid evidence to your claim, take note of the XP Tablet Editions that tried to pushed Tablet PC computing on the go. The desktop has been around for ages and will always be needed for pointing on the screen without obstruction by hands, obscuring elements on the screen.
Also, the mouse/trackball and keyboard will also be needed for prolonged computer work and quick, extensive text entry and a way of navigating MANY CLUSTERED elements shown simultaneously on the screen that is limited in size to fit it all in thus concentrating the density of information and layout - touch interfaces at the moment cannot do this because of the physical nature of hands obscuring elements and having to account for the larger space of the finger press area.
However, I can say this that a pen/touch interface CAN be much quicker than sliding and zeroing the cursor on a button or element. It can also not stress your wrists, given that the tablet is laid flat on your lap, like flipping and pointing in a open read magazine.
If any complaints of the desktop going away is there, it is mis-interpreted in the fact that the desktop tile on the Start screen is not prevalent and marketing of Windows 8 shows only and mostly the Start screen. That tile is there to go back to the desktop, and even more so to boot into it - but ther user will ultimately launch the start menu/screen to open things upon booting anyways...? On a demoed Nokia tablet, that desktop tile is not there (possibly by default). A search for "desktop" will launch it however.
Will you feel the same way if the particular Linux flavor of the year will stop support only to either get down and dirty to home grown your own solution (both the OS AND your third party software along with it) or to wait until someone offers their time and effort to provide continuing support.
I would not mindlessly say that Modern/Metro is casual. It offers merits in a faster pointing method much like other tablet interfaces. But keep in mind about obscuring the screen physically and the dense on screen elements given a fixed screen size and resolution. The advantage with the Modern areas of Windows, compared to say the Samsung Note tablets, is that it definitely feels like what the Windows tablet areas should be.
This includes:
Offering a taskbar (not known right away, since by default, mousing or swiping the left edge merely switches to the next app)
Start screen launcher
An "all applications" listing (though I have gripes about this area)
Application menu bar that is application dependent
Common "window" functions (charms bar can be viewed as such)
A way to search things from the Start screen (charms bar functions)
Along with tiling multiple apps - up to three, if you can set the Modern scaling areas to "smallest"
Multiple user access accounts and privileges.
Samsung's tablets seem to be more about switching screens left and right breaking some cohesiveness instead of scrolling and widgets spaced everywhere with not a distinct feel of a difference between an app or a widget (the Live tiles are distinct than the actual apps for Modern areas of Windows 8).