From Fedora Project Wiki

If you look at Windows or OS X, you'll find that they don't have a ton of semi-random icons in their application menus.

The goal here is to not show icons in buttons and application menus in general. This does not affect application icons in the main menu or bookmarks or places. For these special cases, the icons will remain.

GTK+ needs some improvements before these changes are feasible. Menus need to always have consistent padding on the right, regardless whether there are any check or radio items in the menu.