The less forest that there is left after the fire, the easier it is to clear the rest and replant with tree species that are better at holding onto water in drought conditions, and/or species that are hardier in the face of heat exposure.
The native trees in CA are types that need forest fires for the next generation of seeds to grow. Obviously there are many different trees with different ways to breeding, but we would lose biodiversity if CA followed your plan.
What CA needs to proper forest management, which means different things to different parts of the state. Often parts of that mean regular prescribed burns (which courts have historically stopped - lesson learned: shoot smokey the bear...)