Automatic display full screen, is a helpful feature when view/editing a document , only focusing on the content, however, in G-Documents, full screen limits other functions.

Some examples are:
→ Perform any action on the top panel or notification panel while viewing a document.
→ View / Edit (Google Docs) a document, as compared to other, half screen (aero snap?) With another viewer / editor (LO Writer, Evince, etc.)
→ Any action to manage windows in a single workspace (not all users use multiple workspaces).

The advantage of G-Documents is able to manage and organize all your documents in one place and be able to use their viewer and editor features integrated Google Docs in harmony with other applications on the desktop. Unfortunately, having everything in one place, does not mean you are working with a single document at a time ,and less at a time when requested and uses multitasking systems.