Another thought experiment…. please bear with me.
Why do airlines take luggage away from passengers and store it in the hold? Check-in, baggage collection, misdirected items etc…
What about having fold up seats with a bin underneath each seat sufficient to take a standard wheelie suit case, recessed into the floor. Passengers board the plane with their suit case, find their seat, lift seat and stow the luggage, fold seat down and buckle up.
Luggage would still be scanned for bombs or drugs, and any overweight would be charged. Any oversize cargo (that does not fit into the standard bin) would be stowed in some other on-board locker.
Seems to me would save a bit of time and hassle for the airline. Less luggage getting lost, and passengers responsible for handling their own. The belly cargo space can be used for air freight.