More specifically, Matthews said Clinton's speech reminded him of America's unapologetic approach to foreign policy before the Vietnam War, which can indeed be equated, at least in part, to JFK.
I was a fierce opponent of the Vietnam War. It not only was unconstitutional but unwarranted, and it nearly tore the country apart. I got teargassed in Washington protesting that war, and was barely able to bring myself to vote for Hubert Humphrey over Richard Nixon in 1968 because of it. Matthews is right that among its many casualties was the bright, bold view of America as the leader of the world, and the best it has to offer.
Significantly, although JFK indeed got us far more involved in Vietnam than we should have been, it was LBJ who expanded this into the all-out war and disaster it became. It was therefore JFK's assassination, more than JFK himself, that tragically set this in motion.
Although we've had our great moments in foreign policy and world affairs since then - including, in different ways, from Nixon (opening relations with China), Reagan (end of Soviet Union) and Obama (better relations with Iran and Cuba) - we've yet to regain that sense of confidence and moral leadership that we had under JFK.
Hillary Clinton's speech this afternoon was the first I've really heard or seen of that since the early 1960s, when I was just a kid. Not only is it an inspiring tonic for the insanity of Trump and the dangerous isolationism of saner people on both sides of the isle, it is a blueprint for a better America and a better world, which as the speech made clear, is increasingly one and the same.
I don't know who wrote this speech, but I'm sure Ted Sorenson would've been proud.