I wonder if the earlier Windows 95 style with a few choice icons was a deliberate design decision, or just a budget limitation? I'm thinking it's probably the latter. Funny how a limited budget often leads to better results.
I think the convention was that if the same command was activated by a menu item and a toolbar button, you put the icon from the toolbar button next to the menu item. This also tells the user that they can access the command more quickly in the toolbar, and doesn't force the user to only learn the toolbars by hovering the cursor over every icon.
