All these issues can be addressed relatively easily - and in doing so, Metro would become a hell of a lot more useful for people who want to do actual work on their computers. People often point to Microsoft's collected usage data, saying something like "only 10% of Windows users have more than x number of windows open". The crazy thing is - 10% of all Windows users is still close to 100 million people.
My list of suggestions is short, easy to implement, and does not, in any way, harm the design ideals behind Metro. In fact, I would argue these can be implemented even before Windows 8 goes RTM.
- Instead of just an 80/20 split, allow the window manager to support several splits; or, better yet, do not define any arbitrary split presets at all and allow users to slide the divider to wherever they want. It may be prudent to only enable this for users with larger displays.
- Give classic applications a presence in the Metro application switcher. This makes using them - inevitable due to a severe lack of Metro applications - a lot less cumbersome.
- Allow users to snap individual classic applications in the split view, instead of the entire classic desktop as a whole. Again - this makes using them far less cumbersome.
- The Internet Explorer tab bar needs some love - at least gives us an option to make it persistent so we don't have to right-click in an empty area or reach for the keyboard. I would greatly prefer an option to make it smaller, too; if you hit the two rows it moves from ridiculous to batshit insane.
- To further increase the usefulness of Internet Explorer - turn browser tabs into full-fledged Metro citizens, so they can be added to the application switcher. This would also make it possible to snap them.
That's it. Nothing earth-shattering; just some minor suggestions to make Metro better suited for desktop use. It doesn't address all the problems I'm seeing, but certainly the most pressing.