In the Kennedy case, of course, not everyone would agree that Caroline's Uncle Ted has been a boon to the nation during his years in the Senate -- quite the contrary, since he has long been one of the most liberal lawmakers on Capitol Hill. That's without even taking into consideration the minor matter of Mary Jo Kopechne, the young woman he killed in a mysterious car wreck in 1969.
Other Kennedys have fallen short in office. Joe Kennedy, son of Robert, was known as a telegenic lightweight during his time in the House of Representatives. Rep. Patrick Kennedy (D-R.I.), son of Ted, has made news mostly with his drug use and traffic accidents. Kathleen Kennedy Townsend, daughter of Robert, was elected lieutenant governor of Maryland, but in 2002 managed the feat of becoming the first Democrat in more than three decades to lose a governor's race in that state.
So what kind of Kennedy would Caroline be? Beats me. One way to find out would be to let her run for some entry-level office where she could learn the trade and make her quota of beginner mistakes without doing much harm. But she apparently feels no obligation to show she's up to the job before taking the oath.
You could say the same about her predecessor, Hillary Clinton, who had never held elective office before. But Clinton at least gave the citizens of New York the chance to assess her qualifications before ascending. Kennedy sees no need for such tedium.
Under the customs of hereditary monarchy, her appointment would make perfect sense. But if New York prefers that method, it might as well go with the real thing. Last I checked, Prince Charles didn't have any better offers.