The Executive Summary of the Framework Element of the City of LA's General Plan (1995) asserts that we must "preserve single-family neighborhoods by focusing any growth away from them and into centers".
Let me state up front that this Centers Concept is politically intelligent. Even suggest changing the low-density single-use character of a typical suburban neighborhood and most suburbanites look like they're about to bite your head off.
As a matter of good policy however, the pro-suburban ideology this recommendation represents is fundamentally flawed. This is one of the central conflicts of planning. How densely should we build and which uses go where? Somehow Americans got it into their heads that the only decent neighborhood is one where everybody has a detached house, two lawns, no jobs anywhere close by and so much curb space that every resident could own and park 10 cars without the slightest inconvenience.
Listen to the language. Suburbia is under attack. It needs to be "preserved". From what? Apartments, people of color, the poor, the ability to use a mode of transportation besides driving? I don't share the view that these things are bad.
A resilient, sustainable city has to be a diverse city, with different housing options. It has to be a walkable city, with a form that puts destinations close by so we can kick our habit of driving for every little thing. These things are good not just in centers, but generally. If we leave suburbia out of these changes, we will fail to make urban regions that protect the environment, resist the next oil shock, and provide a measure of social interaction across the boundaries of class and race.
Honestly, suburbia doesn't need to be protected from a little density and some mixed uses. Society needs to be protected from the ideology that says only one kind of housing is good and only one mode of transportation will be possible.