The BA pre-flight dining options ex-NA are only available for those departing from eastern time zone airports (with the exception of ORD). The main reason is because the duration of these transatlantic BA sectors leaving from these cities are often not long enough to enable passengers to enjoy an extended amount of sleep onboard. Thus to maximise their sleeping hours, people often opt for their dinner meals prior to boarding, hence the concept of the pre-flight dining. I've never done pre-flight dining at JFK before, but I have done so prior to taking my BA F flight ex-YYZ and ex-BOS for that particular reason.

All CX departures ex-NA have scheduled flight durations of more than 13 hours, leaving passengers plenty of time to enjoy both in-flight dining and long hours for sleeping.