iOS and OS X are great, but iTunes is the crucial foundation for its iPads, iPhones, iPods, and Apple TVs. Because it is not literally an operating system, I think Apple hasn't yet realized how detrimental it is for them strategically to have such terrible software occupy such an important position in their business. Syncing across devices means that Apple sells a chain, and a chain is only as strong as its weakest link.
And iTunes is a very weak link. When Apple denied rumors of Steve Jobs's worsening health, I didn't believe their denials, and iTunes is why. There's no way on earth iTunes would still be in the condition it's in if Steve Jobs hadn't been too preoccupied to give it his attention.