Dave Taylor suggests we shouldn't...
...And the Chief Executive Officer? Their primary role is to raise money for the company. They are the lead on strategic planning (along with the Board of Directors) and are somewhat involved in corporate tactics (though that's really the purview of the President of the company), but notice that I didn't say anything about "communicating the company message" or even "inspiring the employees" or "engaging customers". For companies of any size, CEOs have more important tasks than writing articles for the company
But... communicating with constituents is central to the CEO's role. True, they may be prospective or current investors as well as customers and employees ... but it's all about communication, in any case. Blogs can in fact be the most leveraged (with nice unintended consequences, some times) medium for communicating with all those constituencies.
But I agree with Dave that it's tough to find the time; one has to be aware of unhappy SEC and FTC-consequences; and, most importantly,
I want strategic business blogs that are written by authorities in the company.
But some CEO blogs meet that criterion...