I think it's about moving home. I think if California is home for someone , then yes, they'd probably be "morose" living somewhere else. But, if leaving California is returning home then the move means more than a financial upgrade. If I were at home here, then the chance of selling our house and buying an especially nice one with cash left over wouldn't be appealing. I think that the Okies leaving California is only partly about retiring with a wad of money left over from the sell of your CA house. It's about not being at home here. I know born and bred Californians who say the same thing. There is a feeling of not being home which adds some appeal to the "sell your house" plan.
You make very good points. Some of the things my out-of-state relatives don't like about California are among the very things I appreciate and missed when I lived elsewhere.