When Microsoft announced Windows 8, they showed that it contained both the familiar desktop environment, as well as Metro, their Windows Phone 7 tile interface. According to a recent column by Mary Jo Foley, Microsoft may scrap the desktop interface on the tablet version of Windows 8, only affording the user the Metro interface instead. From ZDNet:

However, if my Windows Weekly co-host Paul Thurrott is right, Microsoft has rethought that plan and is leaning toward cutting the Desktop from Windows 8 ARM tablets. That would mean only Metro-style apps would be supported on that platform. (Thurrott just dropped that bomb while we were taping Windows Weekly on December 1.)

While some writers—such as John Gruber—focused on the hardware issues faced with running classic Windows apps on an ARM tablet, my issue was actually using an interface not originally designed for touch. I have had the displeasure of operating both my Mac and Windows machines via Splashtop Remote on my iPad, and it is anything but productive. While I am sure the hardware is one reason to not support classic Windows apps on a tablet, for me the bad experience would be the main reason.