I think that having a datatype of the kind 'link' would prove to be a useful thing for the platform.
Every application has a menu. And all the menus suck. It's an awful process to add options to menus, and the normal solution is always an ugly hack. If we had a link datatype, for the static entities at least, we could specify where a given menu or sub-menu would point to. That attribute might also have parameters the same way an external URL has.
If we had this, instead of adding each and every option by hand, hard-coding it in the normal 'menu' web-block, we would query the menu and sub-menu items and make it dynamic. To add a new menu, we would only have to add a record to the static entity and fill it's attributes.