Been a long time coming
Historically, Symbian has never been a compelling and efficient platform for developers. Developing for it today is still a pain compared to iOS, Android or even WinCE (or whatever they're calling it this week). Even the foul bitter BREW is now easier to swallow.
At the same time, Symbian has had an horrific amount of money spunked on it. The dev team has (or had) hordes of cuntractors gouging £500+ a day while twiddling their thumbs and waiting for the demoralised, high-churn permies to produce requirements for features that nobody would use.
So farewell Symbian, you won't be missed.