It seems like every other day we here of a Microsoft employee is leaving the company. But why? What's happening inside Microsoft?
Mattrick was only at Microsoft for 6 years. http://en.wikipedia.org/wiki/Don_MattrickI don't know that this is the case, but MS has also been around long enough for people to be retiring after putting in 20 or more years there.
Probably for the same reasons most of us change employers. The days of getting hired at a company and staying there till retirement are long gone.