Turns out you're right. I had the mythic recollection that JFK did in the hat, but this website set me straight: <http://www.snopes.com/history/american/jfkhat.htm>
I think fedoras are great and can't imagine why they vanished. They look better and give better protection from the elements than those god-awful contemporary baseball caps, which -- with that ridiculous adjusto-strap design -- have an embarrassing way of spotlighting the bald patch on the back of wearers' heads. Why Americans are so drawn to clothing that accentuates their cluelessness is anyone's guess.
Let me stress that what I like is the classic fedora, not that attenuated version that was the hat's last gasp in the early '60s. Tom Wolfe termed these fedoras, with their vestigial brims, "Madison Avenue crash helmets." Karl Malden was the last person known to wear one in public. 'Nuff said.
Something else I'd like to see revived is the coconut straw hat that was popular in the '50s and that golfer "Slamming Sammy" Snead helped popularize. Golfing's a bore, IMO, but the coconut straw snap-brim hat is pretty nifty.
Carl