I think that the discussion over how much “extra” fuel people take is a bit of a red herring. You can get short of fuel through changing circumstances no matter how much you took to start with, so it’s really down to what you do with what you’ve got left, which the crew in question appear to have executed to the best of their ability. Statistically you expect this kind of thing to happen, albeit very rarely, and these guys were presented with something that most pilots go through their entire careers without experiencing. Nothing was broken and nobody got hurt, which is the desired end result - Reserve Fuel is there to cater for these exact kind of situations, it’s not unusable, just that you never plan to use it.
It’s all very well saying you would take more fuel and divert early, but you are still vulnerable to unforeseen externalities. You can’t load fuel for every eventuality as you would be too heavy to take off, so there must be a balance. Personally, I find FP fuel adequate for most of the flights I do but have no hesitation in loading more when appropriate; what I don’t do is add an amount to every flight whatever, as that feels unprofessional - I am paid to be safe but also commercially aware. If I can identify a reason to uplift more and think that it will noticeably increase the chances of making it to destination, then I’m happy to do it as it actually saves time and money in the long run.