This is probably the reason why someone else wrote it. Because writing in "your voice" but without filling words is incredibly hard. But then, it's not the CEOs job to be a good writer.
Being a clear thinker (role of the CEO) and being a concise writer are two different things. The latter requires a lot of training. The CEO of the world's (second) most value company must be able to clearly articulate his goals and his vision, but he doesn't have to be a wordsmith to put his vision on paper.
Writing != thinking != talking
Writing might make you a better communicator in general, maybe a better thinker, too. But clear thinking and talking don't make you automatically a better writer.
I think CEOs (and even senior managers) end up communicating in writing to most of their teams most of the time, so clarity in written communication is essential to top tier people.
