No one likes to talk to strangers on a plane. When we visit a doctor's surgery or clinic we choose a seat in the waiting room that has at least one seat separating us from the nearest occupant. But on a plane we have little choice. You sit with whom you are stuck with and because (in economy) the seats are so tight you feel that your speace, or at least your privacy, has been invaded. And you never really know who you are stuck with!