I completely agree that prices on Apps have come down but that is just what happens when a new market is created. Supply and demand has to set in. Developers are guessing what people will pay at first and if they find they can sell millions more if they just drop the price to 99c then they might just do that. In my opinion the Apple App Store has had very little to do with those prices coming down.
While I do admit the App Store was incredibly innovative and has ushered in an era of new ways for developers to create/distribute/monetize this stuff it is hard to deny that if there was any competing way to load Apps that the 30% fee Apple collects would stand... not to mention the many practices that developers (and consumers) disagree with that Apple regularly does such banning apps that may compete with their products or somehow upset them.
Edit: I don’t want to come off as overly negative here, I love Apple and their products. I am simply arguing that a little competition here would do consumers good.