The simplest and most plausible explanation comes from, of all people, John Dvorak
One of the mysteries surrounding Steve Jobs' decision to hand the CEO title over to Tim Cook is its timing.
The assumption underlying most of the commentary these past two days is that Jobs must be really really sick -- which is understandable given the wording of his letter of resignation. But is he that much sicker this week than he was last week? Or last month? He's clearly not on his deathbed. By several accounts he spent much of the past two days at Apple (aapl) headquarters.
In his "Second Opinion" column for the San Francisco Examiner, John Dvorak -- a man whose penchant for contrariness led him to suggest in 1984 that nobody would want to use a mouse to control a computer and in 2007 that Apple "pull the plug" on the iPhone before it's too late -- offers a simpler, more logical explanation.
"The reason," he wrote, "is Tim Cook." The key paragraphs:
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Everyone in Silicon Valley would love to hire this guy, and from his perspective, his title as “acting” chief executive gets old fast when you are actually running the company.
Jobs has been on extended leave for months, so what’s going to change with this announcement? Nothing, that’s what — except the title itself. And this is what is important.
Giving up the CEO title to Cook had to be done sooner than later. The company cannot take a chance that Cook might get be tired of being jerked around. More importantly, from Cook’s perspective, he cannot afford to be the acting chief executive if Jobs actually dies while he is acting chief.
The way these companies operate, they will keep a CEO if he or she is the actual CEO and the chairman/founder dies. If he or she is the acting CEO when the chairman/founder/CEO dies, then the job is up for grabs. Cook would not automatically become the CEO.
In other words, Cook may get screwed out of the top spot when the weasels come out of the woodwork. “Yes, he’s the acting CEO, but let’s just look around before we give him the job — just in case.”
As one of the commentators on Investor Village's AAPL Sanity board wrote, even a broken clock is right twice a day.
UPDATE: The Form 8-K that Apple filed with the SEC Wednesday to register Jobs' resignation includes this provision:
"In connection with Mr. Cook's appointment as Chief Executive Officer, the Board awarded Mr. Cook 1,000,000 restricted stock units. Fifty percent of the restricted stock units are scheduled to vest on each of August 24, 2016 and August 24, 2021, subject to Mr. Cook's continued employment with Apple through each such date."