The problem is that the airlines want as much as possible of the cargo space free for profitable freight, and for many passengers this now means that the more they can get in the cabin the less they have to pay in surcharges. If they CAN grab their bags they will. The BCs might not be keen on smaller overhead lockers as that would cut freight capacity.
Perhaps corporate bean counters should admit to some responsibility for this behaviour.
Yeah I know, "dream on"!