Oh, BTW, comparing WinCE, Symbian, and Linux with each other requires a very in depth analysis. You can't just argue Linux is open and the other two aren't.

Symbian has capability-based security. This is very important in order to create a secure device, and if you pay by the minute (or by the MB) this is dangerous for dialware. Besides that, as you put, bandwidth is limited as well. You don't want thousands of zombie phones. Besides that, device also contains lots of personal data like a standard desktop.

Apple's moderation on their iPhone is mostly a farce to protect Apple and telcos interests. For example, an application similar to Joikuspot is banned from the AppStore, while many people use Joikuspot on their phone. I've seen it in trains.