The oft used point about eating before flight and therefore no need for on board food is a spurious one.
It always assumes that the customer has had plenty of time to eat before boarding or has time to que up and buy food for on board consumption.
This is not always the case. People may have got up at some ungodly hour, driven to the airport in heavy traffic, stuck in long lines at check in and security and then find the flight is boarding so no time to even grab a coffee.
Others may have arrived on a longhaul flight and assume that they will get the same level of service on their short haul leg.
Also the fact that BA in its infinite wisdom has decided no cash means service is further limited on board and if you are seated in the wrong place you may never be served.
A bad move in my humble opinion.