Sure, from the business end it seems like a good decision, and for one developer, all of whose games run on a fairly unified engine, it may be viable. For the rest of the developers, especially with more demanding titles, this isn't true. Apple can't continue in it's current practice and adopt gaming as a feature to put on the box...they've got to give up something about the aspect of their hardware and business models in order to not give up gaming. Better hardware in more timely intervals, combined with more open software and developer controls - these demands, combined with the classically-radical and immobile nature of Apple will make it a long time before you'll see games (on the PC level) on the Mac, if ever. The rest of the developers are on stand-by, waiting for Valve to get the hard work (which is several years, if you ask me) done with Apple, then they'll all come flooding through the door saying "me too!".
And then, finally, the Apple users will complain about their machines. "What do you mean a 130M can't play Crysis? It's a Mac!"