Ultimately it's a consequence of privatization. Power in California (and particularly PG&E) has been poorly managed for decades and focused on profit at the expense of safety measures, maintenance, etc. Even if these blackouts were a necessary safety measure, the way they were performed is a great example of this - they failed to properly notify customers, their website was broken, their services available for people with medical needs were inadequate, etc. The only way to explain how poorly it was handled is cost-cutting - they had plenty of time in advance to prepare for this.

I'm not really sure whether strong regulatory oversight of PG&E would fix things or if the state just needs to take over. I'm sure privatized power works in other places but I've lived in this state for decades and PG&E has always been a disaster company with a high death count that pays out to investors and execs aggressively.