Earlier quoted context omitted.
I look at it as a more public exit interview. I don't doubt that his expressed concerns were part of why he did leave (I also don't doubt that there are other factors)), and by making those concerns public there's a chance that more people may see it and try to rectify the problems.
Yeah, but in the entire history of people quitting and writing "letters to the editor", has any manager ever actually read it and thought anything other than "whatever, dude wasn't on board, glad he left"? Do you really think Sergey Brin or Larry Page or Eric Schmidt are going to read this and think "oh man, we better change what we're doing". Nope. People who are fans of MS are going to read it and say "yeah, see, I…
So, what's YOUR plan?