It leaves the UK around Breakfast time. Okay 8.30, but some medication needs to be taken an hour before food. Some people arent hungry when they wake up.
However the flight arrives at JFK at around 11:10 am. So its a good hour or more before lunch. So some people would prefer a coffee etc then. They can then have a better meal when they arrive at the destination, either the airport or hotel etc.
I know that its still being a long flight and there are changes to the time zones.