Security by design is a methodical process, not an ad hoc undertaking. Failure to adopt this mindset for every single IoT device will likely lead to the need to make quick fixes to address bugs or newly discovered security threats.
We, as a society, have to decide what the balance is between giving our security intelligence and law enforcement agencies the tools they need and safeguarding the privacy and immunity from eavesdropping we crave.
Why terrorism threat levels rise in the days, weeks and months before an attack, not after. The risk level is determined by what we know, not what has just taken place. And what we know is usually determined in large part by intelligence.