Space is a major issue, people on mobile devices can only tap on things about as big as the end of your thumb. Trying to provide the desktop toolbar would only allow 3 or 4 items. At which point Firefox would be creating a duplicate view of the home screen and the tiles. You can pin specific sites on the tile view by long pressing on the image. https://support.mozilla.org/en-US/kb/use-awesome-screen-search-web-bookmarks-and-more#w_access-your-top-sites