Given the amount of cabin baggage likely on the floor and under seats (because all the overhead lockers are full of piano sized suitcases) it may expedite getting out of your seat to take the junk on the floor with you.
I am a regular passenger on BA, and BA (specifically) need to start applying their own carry on baggage rules to those that fly BA . . .
But it's time to give the 'all PAX are idiots' broken record a rest, 'all flight crew are incompetents and/or mass murderers' is just as imbecilic . . . despite the fact that your kirk has intentionally murdered multiple plane loads of people and killed many more by being unable to do your job and fly the plane properly or opening the doors into a smoke and flame filled environment . . . while PAX offloading baggage in ground evacuations has NOT killed even a small percentage of that number of people . . . perhaps think about that before blaming everybody else . . . as usual . . .