I hate to say this, but perhaps airlines need some regulation by the Feds. Not that the Feds will do a good job but this is really just getting out of hand. I think, for safety and sanity sake, each passenger deserves some minimal amount of cubic sq ft including a reasonable luggage space.
By the way, I just want to mention that southwest, frontier, alaska, virgin america still have 24 by 16 by 10 carry on size.