This change in functionality was introduced in the hotfix that was created to address the issue that is described in the following article Microsoft Knowledge Base article:
313937 The program stops responding when you try to open or to save a file in an Office 2002 program, in an Office 2003 program, in an Office 2007 program, or in an Office 2010 program
The hotfix package for the 2007 Microsoft Office system can be downloaded from the following article in the Microsoft Knowledge Base:
973931 Description of the 2007 Office system hotfix package (Mso-x-none.msp): August 25, 2009
The functionality that was introduced in the 2007 Microsoft Office hotfix was later added to Office 2010.