We use to be able to set page icons for pages. It would be nice to be able to do this again and also maybe even be able to choose from those available from bootstrap versions or any added icons such as font awesome!
Of coarse I can make my own menus that can do this however I use to like adding icons to pages and now that feature is unavailable from what I can tell.
When/If you add this feature again just added a suggestion.
It would be cool to add this to the WYSIWYG editor as well. The ability to use the free icons and see them to add to posts for easy fun. It would also be cool to add your own iconsets that you create uploading them as you create them and being able to access them easily in the editor and page options.
They are widely & commonly used so why not?