Support 'promise'd drag & drop content, e.g. from Photos
You currently cannot drop a photo from Apple's OS X Photos app to Outlook (nor to other Office apps). The reason is that Photos uses the new kPasteboardTypeFileURLPromise / kPasteboardTypeFilePromiseContent format, because it doesn't necessarily store the photo locally, but rather in iCloud.
I'd like to see the behavior fit Apple's Human-Interface guidelines, which are found at https://developer.apple.com/ios/human-interface-guidelines/interaction/drag-and-drop/ Specifically the part that says "Make drag and drop available for all selectable and editable content. Selectable content should be draggable, and editable content should accept dropped content. Also make sure your app supports copy and paste in these areas."
Stewart Alsop commented
When I add a photo to an email, I cannot drag and drop from Photos. Instead, I have to open the Photo Browser in the Pictures drop down menu.
-It starts with the oldest photo in Photos, where I have more than 30,000 photos so I have to scroll all the way to the bottom to get to where I am most likely to select the photo I want
-When I have inserted the photo, it often is inserted upside down
-When it is upside down, there is no "rotate" commend in the photo editing menus.
-The method for resizing the photo is counter-intuitive.
Since the Macintosh is a great platform for photos (with the exception of all the bad features in Photos app), it would be great if Microsoft would use the native photo features (like drag and drop and resize) rather than doing something weird and non-intuitive and different.