Why Your iPod Doesn’t Have Bluetooth - Apple vs. the MP3 Accessory Market - Popular Mechanics:
And that is why Apple likely fears Bluetooth: It would act as a great equalizer for the accessory market. Up until now, a self-feeding economy of scale has allowed Apple (and Apple-licensed products) to utterly dominate the accessory market. If you’re an accessory maker, it’s in your interest to cater to the player with the largest market share. If you’re a consumer looking to purchase a player, it’s in your interest to purchase a player with the largest number of add-ons and accessories. In both cases, the iPod wins.
If Bluetooth found its way onto the iPod, almost overnight Apple would see the accessory gravy train hit the brakes, if not completely derail (the iPhone’s incompatibility with some biggies makes you realize they may already get this). But the add-on implosion would come because Bluetooth not only makes the accessory market more universal (Bluetooth-enabled accessories should work equally well with any Bluetooth-enabled player, regardless of manufacturer), but it circumvents the core of Apple’s accessory stranglehold: the proprietary iPod dock.
If your iPod had Bluetooth, it could sync with your computer without a connector cord. At up to $20 a pop at most stores, these cords are big business. Likewise, if your iPod had Bluetooth, it could connect to any Bluetooth-enabled speaker (believe me, if Apple gave the iPod Bluetooth, these now-rare products would become far more common) without plugging in to that proprietary dock. This would be great: You could even carry your player around the room, changing songs as with a remote while the player streams music through your speakers.
The problem is, if Bluetooth became the standard connection between MP3 players and accessories (or computers), there would be little incentive for third parties to lay down the licensing cash to include that little proprietary dock. And Apple would be foolish to allow that to occur.