Carbon monoxide detectors aren't just there because of natural gas appliances. They're also essential to protect people in cases exactly like you mentioned -- a temporary tabletop camping grill.

It's frightening to read about people who don't have CO detectors and put a combustion-powered generator in their house when the power (and thus heat) goes out in the winter. As of a decade ago the rate of CO deaths was around 400 per year in the US. Whatever it is now it's still terribly high.

For a sad time here's a random article from news.google.com when searching for "carbon monoxide generator" https://www.nbcdfw.com/news/local/2-Boys-2-Men-Dead-After-Ca...

You can heat and cook food during a prolonged power outage, but that's kind of it as far as "essential" goes.

You can't heat your house during a power out, even with gas, because the furnace won't light without power to run the blower (to prevent overheating and therefore fires). But you can heat at least one room in a power outage with a gas fireplace (been there, done that - for hours, though not for days).

There are lots of heating systems (steam boilers, for instance) that don't require blowers. And your gas-heated hot water will also let you continue to take hot showers.

The vast majority of heaters in Berkeley are wall-mounted top vent gravity heaters. They do not need power to operate.

Central HVAC is uncommon due to the mild climate.

>Are there occasions where having natural gas available in a house would be essential?

Maybe not in California (Southern), but in colder climates there is definitely an advantage. I was once in a North East Ice storm where there was a deep freeze after a warm spell that brought down the electrical lines. We were without power for 2 days in sub freezing temps and the gas fireplace kept the house warm.

I'm sure in California where they don't require any heat, you could get away with just electric service as long as it remains affordable.

In freezing climates household heating with natural gas is substantially cheaper than electric.

However, that’s probably not a problem for Berkeley, and the infrastructure costs alone probably justify avoiding natural gas hookups.