I don't get why there are Top Sites, Bookmarks, Bookmarks Toolbar (a special thing), and Collections. There are way too many ways to manage saved urls.Then providing access to exactly 0 of them when in the address bar is even more vexing.
Yeah, it doesn't make much sense. They already have the a context menu when you long press a tile. I don't know why they don't allow you to pin from there.