Exactly, the question we should all be asking is how it got to this point. I reckon you'll find a lot to blame with both the utilities and state government, and the existing incentives for both.
No this is solely PG&E's doing. When you write the regulations, you own the blame. PG&E claims it's too expensive to underground its transmission lines (which would prevent fires like these) at a bit over a million per mile. Meanwhile they took blew their safety budget on executive bonuses. You want to tell me that undergrounding around 100 miles of lines isn't going to reduce the risk of fires? How about undergrounding 500 miles? Because in addition to the safety budget, PG&E also spends around $400 million annually on stock buybacks.
I don't particularly care if PG&E remains a private company, but there need to be consequences like jail time for actions that go far beyond mere negligence.