Originally Posted by
artemis
As I said in the TravelBuzz thread, I think it would be a great idea for the airlines to have a standard carryon size. The thing is, we effectively already do: 22" x 14" x 9" (or its metric equivalent). So why not just go with that? What's gained by making everyone who already has a currently compliant hard-sided rollaboard buy a new one that's only trivially smaller?
One of the other threads had a photo from Boeing that may have a clue. With the somewhat smaller dimensions the bags can all go in on their side, meaningfully increasing the number of bags that can be stowed.
I guess they need more space since less legroom means more passengers (and bags). Also by charging flyers to check bags, more are being carried on board and need space.