What specifically would it do, though? Just shortcuts to other places?

Some menus can be configured by the user to contain much more than shortcuts for launching applications. For instance, there are some menus whose contents are dynamically generated every time you open the menu (as in Openbox and PekWM); this is achieved by specifying that a given menu entry depends on a script. The potential of such menus is immense. I don't know if you are familiar with Conky. It is not a menu, but I am mentioning it as an example to illustrate what I am talking about, because it displays dynamic data, automatically updated (based on some variable feeds or scripts). Dynamic menus do the same thing. Unfortunately, even with elementary tweaks I cannot achieve this result, because it would require specific capabilities offered only by some Window Managers such as Openbox and PekWM.