Steam is my friend, I love gaming on my Mac and have no desire to run windows on my machine. I also use a 360 controller to play a lot of my source games too. Its great fun. Add me if you want to play 8 Ball.
To me, the biggest middle finger Apple's flipped our way was the unceremonious removal of the Rosetta support from OS X Lion and onward. That move really shook this buyer's confidence in buying software. Now everytime I hear a rumor about Apple changing chipsets or even announcing a new OS, I don't get excited, I wonder how much of the stuff I bought is no longer going to work.
FWIW, my copy of Starcraft that I bought in 1998 still works great in Windows 95, 98, ME, 2000, XP, Vista, and 7. Haven't tried 8 yet.
There were two points when major changes left a lot of games behind - the OS 9 to OS X transition and removal of PowerPC (Rosetta) emulation. Other than that it was just the odd title here and there with each 10.x release.
To be fair these days I have a lot of my old OS 9 and early OS X games back again via things like DOSbox and WINE and companies like GOG see the demand for these to be re-released for modern systems. You also have the Feral Legends range bringing some of best titles from the last 5 or so years that got missed.
Lately we seem to be getting more and more recent triple A titles as well so all in all after a lull around the Intel transition OS X gaming seems more promising to me.
At the end of the day you can have a lot of fun gaming on most modern Macs in OS X - enough to keep all but the real hardcore gamer satisfied really.