Icons in menus are good visual anchors which leads to better usability, but only if they are used sparingly. An icon for every menu item ends up being worse.
The key here is that the icons next to the entries robustly tied the menu entry to the icon in the toolbar: "this menu item does what the button with this icon does".
Getting rid of the icons in this case means you don't get a hint that this menu entry is an alias for that button (or vice versa).
