Paul Thurrott points out another odd thing about the Windows 8 Ribbon UI in Explorer:

The Microsoft post describing the new ribbon UI goes into great detail about telemetry data, which provides the company with information about what users are really using in Explorer and elsewhere in Windows. And according to that data, the top 10 commands represent over 81 percent of all commands used in Explorer. The bottom 18 percent of commands (by usage) include such things as Open, Edit (Menu), View Toggle, Organize, New Folder, Send To, and Edit. And yet, looking at a Microsoft screenshot of the new ribbon, what do I see in the default first tab? A bunch of commands–including Open and Edit, by the way–that are not in the 81 percent most-frequently used commands.