That's not really sufficient for seismically active regions like the SF bay area. The mains are more likely to develop leaks from the frequent tremors and no amount of at-home shutoff valves will change that.

If you allow new construction dependent on existing natural gas distribution lines, they increase the pressure to accommodate the increased demand. This makes explosions from pipes leaking/catastrophically failing more likely.

I thought it was obvious the long-term goal was to reduce if not completely eliminate the need for natural gas distribution _especially_ in these regions.

https://en.wikipedia.org/wiki/San_Bruno_pipeline_explosion