Our definition of 'bad weather' is definitely changing as we gather more data.

Besides regular weather (which airliners aim to avoid except during take off and landing) there are many other factors at play here. There are several almanacs that are used for fuel calculations & navigation, they are updated annually.

The fastest jet stream (the aviation equivalent of the trade winds) recorded is north of 400 Kph, having that with you, against you or perpendicular to your flight path will have a substantial influence on fuel consumption and flight duration.

I agree with you that it may well end up with a regulatory change but that's one of many possible outcomes here. I will definitely keep an eye out for the report on this flight's investigation. It is going to make for very educational reading.