A minor aesthetic change which requires a minor intuitive leap for the power user is a major change for most home users. Sure, the steering wheel is on the other side of the car, but thats minor. Except that now the user has to learn how to drive on the other side of the road.
I loaded up windows 7 to look. Where's add/remove software? Wait, that changed and I need to set the control panel to classic to see it. Uh, where's classic mode at. Turns out you select the drop down box to Large/Small Icons for it to change the icon selection entirely. What? I spent a while longer searching for where to install OS components (IIS, etc). Minor irritants to me. Major headaches for my Father, Sister, Brother, etc. Even moreso when they call the family tech who can't figure what the hell they're talking about.
I change to the interface IS a change to the OS as far as all by %1 of users are concerned.
Guess what it works.
Classic what? Click what? Where's what?
Just search for it.
Implying the rest just seems archaic, especially from a user perspective.
Have you used an OS prior to Windows 7 and/or OSX?
Search on windows actually working is a huge step forward. Many users have simply not adapted to this actually being something worth trying.
Search on Windows is horribly broken. One of the first "shortcuts" I learned on OS X was Cmd+Space and typing out the application I wanted to run. Spotlight immediately brought up what I wanted. Windows never did that for me, or spent 45 seconds or more with a spinning hourglass to return a document that happened to be named similar to a program I wanted. I don't care if it works better now, they've set a precedent in my mind that it is broken, because it was broken for the ~15 years I used their OSes.
And for reference, if you go to the control panel in Windows 7, "Uninstall a program" is right there on the bottom left. If you want to install a program (like IIS), clicking "Programs" takes you to a convenient menu that lets you "Turn Windows features on or off".
It's not quite how it was, but it's actually more intuitive. I'd imagine that you learned the old way of doing it by trial and error. The new system makes that process easier.
You innovate or you die, and Microsoft is dying. The iPad is killing them. Maybe not quickly and obviously, but it will end Microsoft's dominance in less than a decade.