To me the Jobs letter reads like one from a leader: strong, confident, and yes egotistical. "I know I'm right, this will all work out to your benefit, you made the right decision, but all things considered it seems right to throw you a bone."
The Cook letter reads like one from a battered spouse. "I'm sorry, please don't leave me, meanwhile have some other women if that makes you happy."
Yes. I'm glad Cook wrote the letter, but it does come across as a bit too meek.
The problem with Jobs' confident tone is that he'd use it even for things he was clearly wrong on (of which he'd amend a year later). Sorry, but a leader confesses his wrongs and moves on. He doesn't try to weasel out of it by handing waving and pointing.