Why are we required to get some apps through iTunes instead of the usual App Store? You'd think ALL apps would be through the APPS Store. I would expect iTunes to be for media downloads
Examples?
Are you asking about the Mac App Store and iTunes for Mac (or Windows), or are you talking about the iOS App Store and iOS iTunes Store?
There's a specific case where all apps are downloaded via iTunes: iOS apps downloaded to your computer. They are downloaded via iTunes because they are synced via iTunes.