It was announced in another question that the desktop version of Unity will keep the global menu by default. Here are the facts:

1. The global menu was introduced into UNE to save vertical screen space because at Netbook resolutions the vertical space is limited.
2. On a modern desktop with a high resolution, there is ample vertical space making this unnecessary
3. On the announcement of UNE global menus, Mark Shuttleworth himself said the following:

"There are outstanding questions about the usability of a panel-hosted menu on much larger screens, where the window and the menu could be very far apart."

The benefits of a global menu don't seem to carry across to a high-resolution desktop and instead seem to bring draw backs (increased mouse travel, large distance between the menu and its associated window).

The other worrying factor is that applications seem to be moving away from having a menu bar, and instead of innovating on this and defining new guidelines for moving away from the menu, we are giving it prime place right at the top of the desktop. If applications continue moving away from the desktop we will have an inconsistent experience concerning where to locate application related options/tools depending on which app you are using (e.g. Chrome).

Finally, the current global menu bar implementation doesn't work for all apps, and doesn't even work for all apps in the default install. This means that the default desktop implementation will be inconsistent.

So, there are a bunch of reasons why moving to a global menu is a bad idea, so we need some pretty convincing arguments for why it is a good idea.

What are the reasons for the global menu implementation in the desktop version of Unity?