[citation][nom]enzed[/nom]I understand where Sinofsky is coming from with this letter, but the fact that he left a month after the release of W8 is just too much of a coincidence to ignore.[/citation]
If he left during the development of Surface RT, that would be too much to ignore. More likely, he's gone through a lot to deliver the product; with the completion of a big task, you have to ask what's next...
It may simply be that he's flippin' rich now, and would like to spend more time with his family rather than chase after more money.