Ubuntu/ Gnome has System Monitor under System > Administration that let's you kill any process (roughly its equivalent of the Apple Menu).
Well, I'd have said that was more directly equivalent to Task Manager in Windows or Activity Monitor in OS X than to an option on the applications menu bar.
It is, but in terms of user interface it is in exactly the same place as Force Quit on OSX.
Force Quit is a hand-held and heavily protected alternative to Activity Monitor/ Terminal. It gives a degree of control to the user (and gives AppleCare staff an easy to navigate to option rather than freaking "naive" users with arcana).
Given Job's well known antipathy to task managers, I suspect the UI people had to work very hard to persuade him that Force Quit was a good thing.