Another POV on this is that you can think of the Start screen as conceptually an extension of the Windows 7 taskbar. They both try to unify application launching, switching and notifications (plus instance management and quick actions, in the taskbar's case). So it would be nice if we had more parity and coherence (e.g., ideally using the same or closely related APIs) between what you can do with the taskbar and Start tiles for desktop apps.
You know, you could be on to something. I have an idea... and even though Microsoft would never take an idea from this forum, I'm going to post it anyway.
For a mouse-driven device, bring back the Start button. As an option to the user... whatever.
But the start screen now opens from the left side, moving the desktop over a bit (similar to the how Mountain Lion's notification center opens from the right: https://www.youtube.com/watch?v=8H-fY_N4AMI).
This interface wouldn't be like the old Start menu, but instead it would retain Live Tiles and be laid out vertically in a format much more like WP8. And, include as an option to the user, the ability for the most recent apps to show in the top of the list.
Eh, it won't happen, but I wouldn't mind if someone at Microsoft at least considered it for 2 seconds.