The Carry On Carryings On

Blair and her sister Lisa are frequent flyers.  Blair never checks her bags due to the inconvenience of it, opting instead to carry them on.  Since she’s only 5’1”, she often relies on the generosity of fellow passengers to help maneuver her bags into the overhead compartment.  Her sister Lisa feels that Blair and people like her abuse the convenience of a carry-on -- in short, if you’re unable to completely manage your belongings on the plane, you should have to check them.  Who is right?