Apple's attempting to set a new expectation with consumers: OS updates should be free. Users are already accustomed to it on their phones, now they'll start to expect it of their computers.
I'm willing to wager that Apple never charges for an OS update again. I'm surprised they've taken this long to make the leap. (Of course, Microsoft makes more from OEM licensing than upgrades, but it's still a blow to their value in the consumer headspace.)
No kidding. You didn't buy your laptop/desktop from Microsoft, did you? Maybe you should take up your claim for free Windows 8 with Lenovo/Dell/HP/Toshiba.
Apple and Microsoft are in almost entirely disjoint businesses, anyway. I doubt that there's much useful analogizing to be done about their current respective situations.
Windows 8.1 is about as equivalent to OS X 10.9 as you can get and it was also free.
What exactly is the "boot to the face" here?