Let's see---- there would be a house with a broken pipe among every 2,000 homes with no gas. How happy would you be after a few days living in the cold with those odds of there actually being a hazard?

It is a bit of a silly question.
If YOUR home is one of those that burned to the ground, who cares if a couple of thousand people might have been inconvenienced a bit to prevent it. It isn't like Seattle is the Arctic. People "could" use electric heaters (or toaster ovens, hair dryers, etc) in a small room to survive.

OTOH, if your gas is shutoff, all that matters is your comfort, who cares if somebody else's house burned down...bad luck for them.

Reasonably speaking it would be a good idea for all homes to have shutoffs. Mass production could/would lead to better valves with fewer false triggers and lower costs. It is possible to train a lot of people to be able to re-open after an emergency. It isn't possible to unburn houses, etc.

Mike