I was being glib, of course, but it's difficult to believe that this needs explanation. Apple liked this app and wants it to become a core feature of their products, differentiating one from another. They couldn't very well allow it to live on as a free option if they're relying on it as a feature, you see? I understand that people feel upset that it's been taken away but Apple is betting that the outcome will be favorable to them. One could also argue that Siri will get better and improve over time now that it's been elevated to an A list feature of their flagship product, not just one of many free apps in the app store. Better long term outcome for everyone, though it's a loss for the early adopters.