But weather decisions aren't really that difficult - the problem is pilots thinking they are better or luckier than they actually are.
I'm a little reluctant to say this as I'm fairly sure you have a lot more experience than I do, but I would strongly disagree. In my experience weather decisions are often difficult, especially in a commercial operation. It's hard to know where the limit is without making mistakes and getting into a bad situation, especially in single pilot ops. If you're over-cautious you're likely to find yourself unemployed in short order, especially as an inexperienced pilot. In the area in question there's essentially no way to gauge the conditions without going up and taking a look and 99.999% of the time there is a way through. I knew the pilot on this flight (although not well) and he'd probably flown this route well in excess of 10,000 times. I can still hear him saying "it's only a f'ing tour" when encouraging people to cancel flights and he was one of the first to cancel of all the operators on Kauai. There's clearly no way of knowing the decision process that led to him being in the situation he was in, but he wasn't the type to take dumb risks which emphasises that if it happened to him it could happen to any of us.