I have heard this locker argument on the gatwick flights. And it does just illustrate the point. Its only on the Gatwick flights.
Not on BA LHR to Frankfurt or Stockholm both flights I take a couple of dozen times a year. Ipay £600 for the flight and its a simple fact that on Gatwick flights you have to ask for your jacket to be taken and on Heathrow flights you dont unless the locker is full.
I suspect that the reason is that Gatwick has far more leisure/infrequent flyers the routes are less core business and the combination of lack of push from the top and lack of push from the bottom leaves gatwick suffering.