Office 2013 was designed with touch screen tablets in mind, and to this end, When Outlook is in Touch Mode, the ribbon is a little roomier and useful buttons visible along the right edge of the screen.
This adds the Touch Mode button to the QAT which you can use to toggle Touch Mode off and on.
Although it's less than useful if you don't have a touch screen, if you like the roomier ribbon, you can use it with a mouse.
The first screenshot shows the Home ribbon in "normal" mode. The Touch Mode button was added to the QAT and is highlighted.
When Touch Mode is enabled, a toolbar is added to the right side of the screen (see screenshot below) and the ribbon is roomier. I like the Quick Steps menu (especially on a window wider than I used for the screenshot.)
The Quick Delete, Mark as Read bar, and Flag buttons in the message list cannot be selected by touch, you'll need to use the icons on the Touch bar instead.
Use the touch bar on a tablet to reply (flyout includes reply all and forward options), quick delete, move or copy to folder, flag for followup, or mark messages read and unread.
|Reply, Reply to All, Forward|
|Move or Copy to Folder|
|Flag for follow up|
|Mark as Read or Unread|