Do gate staff have the facility to collect fees at the gate anyway ? Their priority is getting the flight boarded on time, invariably there is only one staff present anyway.
There used to be a time when everyone walking into the gate area at STN got intercepted by staff eager to relieve people of their excess bags and take fees at the desk but that stopped and got shifted to the gate.
As someone who travels with rucksack only which fits under the seat, annoys me watching the antics on the aircraft trying to fit it all in overhead lockers. Just think how much quicker security process would be with less baggage to process.
Aircraft holds are where suitcases should be, that's why aircraft have them.