Changing the subject a bit, isn't The Internet of Things
going to lead to a situation where there are even more NSA, GCHQ, BND
remotely controlled computers with microphones and other sensors all around us

Not if IoT dev's start encrypting things.

On a side note, hidden services are a great model for IoT devices; a la TorChat.

Transparently routing ALL traffic from a computer over tor sounds like
a terrible idea! This will undoubtedly result in sending things over Tor that
you don't really want to send.

From a latency / bandwidth perspective? Or paranoia?