1. Apple doesnt make DoubleTwist.
2. Pre works with drag&drop due to its OS, not due to Apples technical merit. You can plug a Pre into a FreeDOS system and still put things on it.
3. iTunes used to work with the Pre via an iPod simulation by the Pre. Apple broke that intentionally. That sounds like anti-competitive to me and telling people You cant use iTunes to sync if you dont use our hardware."
Anti-competitive doesn't mean what you think it means.
It would be anti-competitive if, say, putting one's music files in iTunes made it impossible to then use them on a Pre.
That's not the case here. Your files are still yours to do with as you please. And in fact, you can still sync with iTunes (using DoubleTwist and other XML solutions).