The Big City; Public Price For the Loss Of a Kennedy
John Tierney column contends that most Americans are probably glad that no expense was spared to find John F Kennedy Jr's plane; maintains that many of them might also have hard time justifying government's extraordinary efforts in case, which officially was nothing more than relatively routine accident involving private citizen; holds that one way to reconcile public's conflicting sentiments would be for someone other than taxpayers to pay for salvage operation; suggests that news media should reimburse government for rescue-and-recovery bill; says New York's publishers and broadcasters can afford to pay portion of profits they have made off Kennedy this week, not to mention last 38 years (M)