a) Large parts of California have fire as part of their natural ecological lifecycle. In most of the U.S., downfall wood rots, but in most of California, it's too dry so it just sits there building up until it catches on fire.
b) People like to live near or in the woods, like they can in other states, so they lobby the government to suppress fires. Suppressing fires causes more buildup of downfall wood. If fires are always suppressed, the energy will simply keep building up until it can support a fire so fast and so extreme that it cannot be contained by Cal Fire.
c) We're experiencing some changes in the climate, and we just got out of a huge drought that killed off a very large number of trees in California.
There will always be ignition sources, whether it's a camp fire, a cigarette, power lines, an arsonist, a truck with a hot catalytic converter parked over dry grass, or lightning, large amounts of combustible material laying on the ground will eventually burn. If we just say the problem is poorly maintained power lines and fix all of them, or turn off the power for weeks every year, nothing will change. The fuel will still be there and eventually something will light it on fire.
I highly recommend this lecture by Stephen Pyne that goes into all of this and has some extremely interesting information about the history of fire suppression in the U.S., and how the Native Americans learned how to effectively manage fire in California over centuries. http://longnow.org/seminars/02016/feb/09/fire-slow-fire-fast...