Online music stores are insignificant.
No one has buys an iPod/iPhone because of the iTunes Music Store. Despite the fact that more than 2 billion songs have been sold over the online shop, when you break the ratio of songs sold per iPods/iPhones it turns out to be about 20 songs per device. I have two iPods and have personally bought 1 album consisting of 12 songs and that over 1 and a half years ago. My iTunes library consists of 3500 songs/175 albums from CDs that belong to my household or have borrowed from friends and family.
Among my known friends and acquaintances that own an iPod I know of no one who has even check out the online store. It is probably the greatest diversionary tactic Apple has conceived of. I am always amazed at how the press (the Register included) harps on and on about the store. The zune failed because it was made to promote MS's online store instead of being design to compete with Apples iPod line.
Maybe someday somebody will build a better music player but it wont be a mobile operator or a software company that does not make its own hardware or a hardware manufacturer who does not design for its end user. As far as I'm concern the iTunes Music store could disappear right now and your so called "stereolithic companies" could be online and in the shops since yesterday - it wont make a dent with Apples hardware sales.
People buy music players to listen to music and the buy phones to make calls, ergo the iPhone sells because it gives most of its customers want they want - an intelligent and easy to use device that plays music and films and also can make and take a call. Everything else is cream.