THANK YOU!
My point exactly. This is not to stablize the OS or any of the other BS. It is to drive hardware sales. Plain and simple.
Well, perhaps that's a little cynical. I would say, simply, that the OS that PPC machines run isn't a huge concern to Apple. They make their OS to give their machines a compelling selling point, and they aren't selling PPC machines any more. It's not necessarily that they're trying to force PPC users to upgrade (although this may be a secondary effect) but that instead they're not going to see enough return (from OS upgrades) to make it worth their while.