The Mac's menu-bar at the top of the screen was a Fitts' Law thing, the same reason why Windows (before 8) put the Start Button in the corner, and why Windows 95 was so brain-damaged for putting the Start button two pixels away from the corner.
Hell, I'm using Kubuntu with KDE right now, and how is it set up? With the K menu in the lower right corner, ready to be quick-drawn at the flick of a mouse.
Though to be honest, the Mac-style menubars don't work as well as they used to. In the early days of the Mac, screens were smaller, trying to get multiple windows on screen just made it hard to get work done, so you maximized your window, had your menubar on the top of the screen, and for those early Macs with small monitors and lower resolutions, that was the optimal way to get things done.
Now with big screens, and multiple screens, people want to have multiple windows up. On my system, I usually don't have my web browser maximized, because it makes columns too wide that way, and makes reading harder, so I have it only vertically maximized. On systems with the huge amounts of screen real-estate, the top-of-the-screen Mac-style menu bar doesn't make as much sense anymore. It's too removed from the application. Some power users will still like it - they're all for quick-drawing their menus, but having the app in one window, and the menus for that app way off on the top edge of the screen is confusing.
And big monitors is why Microsoft's insistence on forcibly full-screening applications is brain-damaged.
My very first job, I worked at an A&W, and they put me to work at the deep fryer. The procedure there (OSHA would not approve) was to take a big bag of fries out of the freezer, cook some of them, put the fries back in the freezer, and repeat for a few iterations. They freeze-thaw cycles would cause the fries to get covered with ice crystals.
One particularly frantic dinner rush, I was scrambling to get fries out, and I jammed a whole bunch of ice-covered fries in the deep fryer. Of course, the crystals flashed to steam, and splashed my arm with napalm-hot frying oil. I still have the scars.