Ambitious and nowhere to go
Certainly, Sinofsky is ambitious and will have looked for more power. The question is, where could he go next? Server and Tools has a relatively new executive, and Ballmer's already shaken up phones and gaming with the departure of Bach. The Online division is an option but a poor cousin to Windows, Server and Tools, and Office; it's struggling against Google and it loses money. Why would Sinofsky want to tarnish his image with the risk of a failure?
The suggestion of a clash with Ballmer has some legs: the aftermath of Sinofsky's exit matches the changes inside Bach's former empire, and that of Business Solutions following the exit of that group's president Stephen Elop: responsibilities of the departing chief are distributed among lower executives who have skills in certain areas but who are denied the encompassing role of a group president.
Ballmer has appointed Sinofsky's colleague Julie Larson-Green, who worked with Sinofsky on Office, to lead Windows software and hardware engineering. Tami Reller will retain her role as Windows and Windows Live chief financial officer while taking on the job of running the Windows business.
Whether it was performance, politics or a desire to make a break, it will reflect badly on all concerned. A cloud now hangs over Windows 8, RT and Surface just as Microsoft tries to get a foothold in its uphill climb against Apple.
Sinofsky said he's leaving for personal and private reasons, somewhat countering the notion he's an executive more concerned about his own future rather than the fate of the team he's left behind and the product that's got his fingerprints all over, which was supposed to lead Microsoft blinking into a brand new era.
It will reflect badly on Ballmer for allowing such an individual to slip through his fingers so suddenly - unless it is for a very personal reason, such as health or a family matter, of course.
Worse, it's damaging for development of Windows as big problems remain: we have a Windows 8 operating system on ARM that doesn't work with legacy x86 Windows apps, and a Windows 8 operating system on x86 that won't bring touch to legacy Windows apps. And, aside from any lingering technology problems, Microsoft still hasn't given a satisfactory explanation of how it will explain the differences between a Windows RT and a Windows 8 device to the average punter.
All we've had is an assurance the problems will be solved. That assurance came from Sinofsky before launch, but there were no details.
Also, there's the cultural challenge that must be overcome: getting users ready for the new interface, of having to switch between sessions for Internet Explorer 10 in the classic desktop and Metro, and - yes - that lack of a start button, that those used to running Windows will want to see.
Hovering over all this is Windows 9, because the answer to all these issues is simple: how far does Microsoft go next? Metro all the way, or does it continue to offer a mix of Metro and classic in Window Next?
There are big questions over whether Larson-Green is the right person to lead this work. Read Mini Microsoft, a blog by an anonymous Redmond worker, and it'll become apparent not only just how polarised employees are on the exit of Sinofsky but also the techies' feelings towards his replacement.
Larson-Green is an ex-programme manager and an interface expert; she worked on Metro and was responsible for the introduction of the Office 2007 Ribbon - something that confused users of Office.
Three weeks ago, Microsoft was riding the crest of a wave. "People are walking the hallways tonight at work, and certainly can't believe it. I can't believe it - working at a Microsoft without Sinofsky? Inconceivable," the blogger wrote this week.
Microsoft without Sinofsky isn't inconceivable - it just happened a lot sooner than we expected. There's even a convincing argument that he wasn't indispensable.
What is inconceivable the nature of his departure. It's an exit that's going to damage Microsoft and Ballmer, it will stamp on the growing self-confidence of Microsoft staffers, and it creates great uncertainty over the future of Windows with so many questions left unanswered at a time when it seemed uncertainty was a thing of the past. ®