which actually makes sense, if you want to keep selling Macs. The demographics of computer buyers are changing away from power-users to casual users scratching heads over whether a tablet is enough. And with malware slowly but steadily on the rise for MacOS, there is a reason why a lot of people from a high-school kid to your grandmother would be better off with a software depot that is safe and proven and offers automatic updates.
It ain't for me, but more and more even I get twitchy downloading something from softpedia or Sourceforge, wondering if someone's messed with the app I want. Tim Cook is trying to maintain the reputation that Macs "just work", and some sort of safe playroom may be the only way to ensure that for the potential buyers he is seeking to grow the line. I feel this... I spent hundreds, really hundreds, of hours cleaning malware junk off people's PC's back in the XP days ("I just downloaded this new bubble game, so why's my laptop so slow?") so I feel entitled to say I'm completely sick of malware.
I know this is a touchy subject for Slashdotters, and damn I don't want my Mac closed off from "sideloading" any more than on my Windows PC or Linux box. But there are too many stories (google them yourself) about Android apps being fouled, and even one or two evil apps squeak through Apple's app store. It's a hostile world, and Cook would be a fool not to try and do something about it because a malware infested machine, no matter what platform, sucks for everyone. I am confident that Apple needs it's power users enough they will never lock-down macs like in like iOS, but a warning that you're about to run an app from an unknown source, require an admin password, is a price I'm willing to pay. Might lead to a few less infected macs overheating and crashing in weird ways.