iTunes wasn't written in Carbon to be cross-platform with Windows--if anything, it would be easier to make a Cocoa app cross platform because you just need to port Cocoa, which is basically just OpenStep.
It was written in Carbon to be cross-platform with Mac OS 9. And because it was just SoundJam MP, which was written for Mac OS pre-X. (Though, to be fair, so was Photoshop.)
It was written in Carbon to be cross-platform with Mac OS 9. And because it was just SoundJam MP, which was written for Mac OS pre-X. (Though, to be fair, so was Photoshop.)