On a desktop or laptop, Metro could also be the PC that people use, while the Windows Desktop portion sits essentially inert in the background, available for those times when users have no choice.
A colleague's wife already regards Windows 8 this way. She's by no means a geek, finding for example that the iPhone has more capabilities and complexity than she needs, so she switched very happily to the dead-simple Windows Phone smartphone. Now she's using a Windows 8 test PC the same way, checking email, accessing the Web, updating her calendar, and listening to music. When she has to go into the Windows Desktop, she regards it as a necessary and familiar -- but fortunately rare -- excursion into the seamier side of town.
For her, Windows is a means to an end. Now Metro is an easier, better means to her ends.
For most people, Windows 8 could very well mean Metro, and they will like Metro. If most people live their digital lives almost exclusively in Metro, the Windows Desktop part could simply be dropped in Windows 9, after its transitional use is done.
Think that's too cynical? Consider the experience of most Windows users I've encountered who switch to Macs. For a few months, they run Windows in a Boot Camp partition or in a VMware Fusion or Parallels Desktop virtual machine to use the familiar apps. But usually before a half year has passed, they realize they just don't go into Windows any more. They can -- and do -- live in OS X. Some are now living in iOS or Android. Many people will be able to live in Metro.
Ironically, the best case for Windows 8 is taking advantage of the part that isn't the traditional Windows. It's a case well worth exploring if your computing needs are simple and straightforward.
Maybe to save Windows, Microsoft has to kill traditional Windows after providing this transition version that helps people let go of the past.
This article, "The case for Windows 8," was originally published at InfoWorld.com. Read more of Galen Gruman's Smart User blog at InfoWorld.com. For the latest business technology news, follow InfoWorld.com on Twitter.