What they don't emphasize is, in exchange for this setting aside of land, the deal is, the developer gets to build 14,000 homes on areas that are NOT set aside for wilderness. The traffic in this area is atrocious as it is and I can't imagine another 14,000+ cars, most of which are trying to get to the 5 freeway during rush hour.
I used to live in CA, and what I don't understand is why the zoning is always for residences. Building mixed use zones, where people can live, work and shop without endless freeway travel makes more sense to me.
But that wasn't the way it was in CA.
Also, reserving land by keeping it from being "developed" helps hold up prices for property that already is developed. A good example of this is in Marin County which is on the north side of San Francisco bay. A very large portion of the entire county is off limits to development.