That's because these areas were unpopulated desert or something which got converted into housing.
By contrast, each of the towns in the Bay Area was a standalone town of its own with its own downtown and rail station etc for a long time. Even today, most Bay Area towns are reasonably mixed wrt residental and business.
All (afaik) new construction for about 10 years has been townhomes, not single-family homes, so I'm not even sure this author is correct wrt housing code.
Just my two cents.
You want a NYC or European-style transportation system, where it's completely unnecessary to own dangerous, unreliable, expensive automobiles. Cities designed around walking -- like the good parts of San Francisco -- are WAY more human-friendly and memorable. I guarantee that whatever parts of San Francisco you love, they're almost definitely not parts you're forced to drive to.
From my city, trains are leaving for Zurich, Geneva, Bern, Lausanne, Basel etc. every 30 minutes.
Most commuters take the train even if they own a car.
I'm still a proponent of urbanization because suburbs seem to disrupt natural spaces. If you travel from east Switzerland to Geneva in the west by train, you will always see a house somewhere, on the entire 400 kilometres of journey. Every village looks alike.
That said, I do think mega-cities can be very tiring and demanding. I only have limited experiences in this regard but cities like Seoul or Istanbul are not the most relaxing environments for its inhabitants.
Besides, LA is not ugly because of the population density, but because of the endless sprawl.
(also similar: minimal amount of nature within the city itself; lots of concrete but not in an elegant urban way; not much in the way of historical sections)
And, when people say "LA", they really mean the LA area, which contains not only the city itself, but outlying/surrounded cities like Pasadena, Santa Monica, Compton, Long Beach, etc.
The article was arguing for density, not sprawl. Also that affordability is more important than desirability.
It's pretty simple. Communities tend to "clump", and people generally aren't willing to commute a really long way so the diameter of each "clump" is limited. Now, this wouldn't be an issue if our population was so massive the entire USA was covered in continuous urban sprawl, but I don't think that would make you happy.
This country is phenomenally huge and there is no reason whatsoever to live clustered together in vile, concrete scabs. Compact cities are more efficient, but congested urban sprawl is most definitely not. Strict building regulations are part of what make this place productive and desirable in the first place.