I used to fly with my kites. The kite bag, broken down, was roughly the same dimennsions as a 3x5 case. They used to stow them in one of the entryway closets for the flight. No big deal.
I do not understand why they cannot use those same closets to put the carry-on cases in. They could even install locks on the closet doors, to prevent general access to them during flight by the passengers. You could pick up your case while disembarking the plane. To further fascillitate a smooth disembarking, I would even be willing to wait to be the last passengers exiting the plane, if it meant walking off of it with my precious cues in hand...all safe and sound.
Any proposals would have to be submitted to DHS, since the airlines have no real control over the 'carry-on' issue, and what is or isn't allowed in the passenger cabin.
Lisa