The benefits of smoke detectors very clearly outweighs the costs of smoke detectors in every household, by a very large margin. Further, smoke detectors are not intrusive. Unless there is a fire (or the battery is running low), most people will not even notice the presence of a smoke detector.
They run on RADIATION!
No they don't. I am not aware of any evidence to support this (including the revised claim that smoke detectors emit radiation).