they are also usability improvements. when you're done reading an article, you're at the bottom of the page. for the average user, having a nice set of option

they are also usability improvements. when you're done reading an article, you're at the bottom of the page. for the average user, having a nice set of options right in front of your face is more convenient than having to click a "to the top" button, or scroll back up, or whatever.