This new Apple TV will be a lot more straight forward IMO. While the computer needs to be ON, that much should be obvious to most people, in the same way that your CD player has to be ON to play music through your Amplifier which is also ON. Or that your car has to be ON to use the stereo in it. Etc...

I believe the process of syncing a portion of your collection to another device is a lot more foreign a concept.