It seems shocking that people would become violent over cramped legroom, but perhaps you understand if you've ever had somebody recline against your knees during a long flight. Two planes have diverted due to recliner-related issues this week alone, specifically over the use of Knee Defender devices. Many airlines have banned the device — which passengers attach to their tray tables to prevent people in front of them from reclining — but it is selling better than ever. How do you feel about the device? Do you care enough about comfortable plane rides to buy one?