What did Windows Vista do? In an attempt to revolutionize UI and "wow" users, it removed direct access to all buttons except Back, Forward and View, and gave users buttons like Burn and Share which they may not use most of the time. It tried to make the toolbar somewhat dynamic (item/selection specific options) like the Office Ribbon but ended leaving a huge amount of empty space on the toolbar. Critically, it removed the ability to quickly toggle the tree view/left folder (navigation) pane. Windows 7 has gone one step further into degrading the "command bar" by removing icons for more buttons except for the "Open" action icon. Windows 7 does add 2 critical buttons though "New Folder" and Preview pane toggle button. Every now and then on some forum or blog, you see users complaining about the lack of an Up button. Fanboys argue that the Up button isn't necessary with the advent of breadcrumb-style address bar but the Up button allowed users to navigate one level up using a static button, the breadcrumbs style requires users to accurately re-position their mouse pointer every time over the parent folder and then click.
Fortunately, a shell extension partially written in .NET and partially in native code called QTTabBar allowed poor Vista
More recently, Classic Shell has become available which does an exceptionally stellar job of permanently bringing the toolbar icons back, well not permanently really, until Windows breaks Explorer toolbars.
Really! What were they thinking? No one would notice & want it back?