This is not surprising, considering that most people who move to GNU/Linux are Windows refugees. And one needs some points of similarity in order to ease the transition.
Even when Ubuntu came along in 2004, though the menu was located at the top of the screen, it was child's play to move it to the bottom. Ubuntu was tracking the development of GNOME, keeping in sync with the six-monthly release schedule of the latter.
But when Ubuntu founder Mark Shuttleworth decided that he needed something different as an interface and could not convince the GNOME developers to go along with his ideas, a split of sorts eventuated.
Unity was unveiled.
Given that Shuttleworth sees the Mac as the platform to emulate, it was only a matter of time before he either asked his programmers to create a design that took in some elements of OS-X, or else tweaked one of the existing environments to do the same thing. He took the first route.
Unity has emulated the look of a mobile phone interface; the intention is to also cater to tablets and mobiles down the track. That's the way business is trending, that's the way any company that wants to balance the books will have to look too.