Having had to wait for lost luggage during or after about a third of all the trips in which I checked luggage, I decided to carry a backpack and laptop and forgo the suitcase.
Of course the backpack is a little thicker than the luggage gauge the airports have, but it doesn't matter since it crushes down easily and fits anyway. The thing is just a little puffy, not densely packed.
Not so some of the items brought on board--at least a third of the semi-hard-sided wheeled packs were never put inside that gauge--they'd never have fit, even empty. On board their proprietors shove and slam and push and twist their packs with reckless disregard for their neighbor's smaller packs and laptops (and then half the time they stand in the aisle to remove coats which they stuff in to take up even more room in the ceiling).
Some items almost fit.
I wonder if there's room on the jetway for a luggage compacter. An aide checks suspiciously large items, and puts them in the compacter for testing and turns it on. If the item is too large in one dimension, it is squeezed down until it fits. If it springs back--no problem, it'll squeeze in place in the luggage rack. If it stays crushed--no problem, now it will fit. If the passenger worries about it being crushed, maybe he should gate-check it...