No, I'm not that surprised. I think this feature is intended to protect your personal data from the casual iPhone thief or to minimize risk if you lose/forget your iPhone somewhere. I don't think it was intended to be a secure-from-governments kind of features.
Guess again - it is! It's a work in progress, and on the 6S it has improved a lot with the secure enclave in its own chip. It seems it will get even better, with encryption in the icloud as well.
The SE uses a different key for each app, so even if you can decrypt one key, you only get data from one app.
