Doctor Glyndwr wrote:
I have a hunch that when we look back the Mac App Store's biggest contribution will be micro payments allowing types of programs that were not commercially feasible before, rather than simplicity to the purchasing process, but it's early days yet. Certainly both factors matter.
I think the buying (and, related, discovery) process is fundamental to everything 'app'. Before the App Store arrived on iOS, it was relatively rare for people to buy mobile apps and games. But rather than Apple suggest it's something people might do, it became the entire cornerstone of iOS, with Apple training and encouraging people to buy software from day one (of iOS 2, obv.). But, to my mind, it's the streamlined UX that makes this a success. The fact there are many millions of credit cards attached to iTunes, and you subsequently only having to click 'buy' and type in a password is a quantum leap in software purchasing.
Along with this, strong discoverability (i.e. the App Store icon on the iOS home screen or the Mac App Store in the Dock or Apple menu) gets more eyeballs, which in turn leads to potentially more products being feasible. I suspect you're perhaps right that the key thing people will remember is the shift in software (many more Mac games; lots of small, focussed products), but it's the purchasing process that enables such things.