Its all comes down to the user. I look around my family and see how they all have different levels of uses and preferences. Simple web browsing and e-mails will work fine with modern touch UI and the simplicity of the modern UI keeps the "how does this work?.." questions to a minimal. For productivity there's no room for modern UI. Using your finger will never be as precise as a 1400 dpi laser mouse, therefore the modern touch UI can only go so far and users will have to put down their tablets and jump on a PC. For now at least... who knows what the future will bring.
As a programmer, I don't want or need a touchscreen style interface to access my development environment. I just need quick and dirty access, and I find the graphical interfaces are more of a distraction than a help. I may have to target the metro, but I don't have to live in it...
The 'Modern' UI seems more oriented toward content consumption, which requires little in the way of navigation or detail management. Content creation, other than "mash-up" style, requires the ability to manage and navigate layers of detail. Modern UI methods don't lend themselves to concise presentation and rapid navigation.
I'd like to see someone develop an effective IDE in the 'Modern' UI. VS 2015, perhaps?
For phones and tablets the Modern UI makes sense. Small real estate, no keyboard, and a low-precision pointing device (your finger) means that detail navigation takes lots of gestures. That encourages apps with low navigation requirements, aka content consumption. The only data entry required is that needed for search.
For the laptop/desktop, I don't think that's the case. Lots of real estate, a keyboard for text entry, and a precision pointing device (mouse/trackball) lend themselves to concise navigation through dense detail and heavy data entry.
The end point is, I think there's room for both approaches. I'm not sure it's necessary to force the Modern UI on the desktop to ensure a commonality that isn't appropriate. I'll wait and see how Windows 8.1 is on my wife's laptop (I'm still running Win7), and see if there are any improvements.
I'd like to see the results of someone TRYING to develop an effective IDE in a modern ui style.
Given some of the bizarre decisions made by the VS2012+ UI team (ALL CAPS menus, fer goshsakes) you may get your wish.
Perhaps I am being unnecessarily pedantic here, but this really isn't true. They are predominantly content-consumption devices, certainly, but it is entirely possible to create a variety of type of images, edited videos and even music with a tablet, and people are doing this.
That said, the degree of flexibility currently possible with touch interfaces does limit what can be achieved, and I don't really see how that can change significantly. Anyone really serious about creating any of these media will continue to use a traditional desktop for the foreseeable future.
I always thought it would be fun to provide additional user feedback on entering stupid data ( "." in text fields is a user favourite here, even when its not a required field) with a mild electric shock mechanism in a keyboard, but I guess that could be done with either a touchscreen or keyboard.
"If you don't fail at least 90 percent of the time, you're not aiming high enough."
I also need more than 1 application at once at home. So still don't see good use for Metro aside from tablets or phones...
I have a Surface Pro at home for ocasionally watching movies, listening to some music and surfing the web, where I like the Metro Interface. I even like Internet Explorer more than Chrome as far as the Metro Implementation is concerned...
I haven't used it yet with multiple monitors. How does this work on Windows 8?
Are you able to run different applications in metro on those monitors? Or is it just for Desktop use again? (How about the Taskbar? Does it finally extend to the other monitors?)