With Office 2007, the main apps introduced the ribbon and with Office 2010, Office introduced the ability to customize the ribbon. Since the ribbon was a major shift in the UI experience, it made sense that only the key apps should “test the waters” and the other apps should wait till the next release. It was basically a “too many cooks spoil the broth” scenerio.
With Visio 2010, Visio acquired the Ribbon AND ribbon customization. One problem with menus in Visio 2007 was their placement was not optomized and it was possible to leave gaps. So the introduction of the ribbon meant a better placement of the buttons and only displaying the relevant ones. (Of course, relevancy is subject to interpretation)
With the introduction of the ribbon, there were some major changes in the UI. One noticable one is the removal of the “Use Developer Mode” checkbox in the Options menu. The user can now directly customize the ribbon to enable the buttons that were added by the old “Use Developer Mode” option checkbox.
There is an alternate way to get to code. On the View tab, the last group is Macros. You can then access or create VBA macros.