Ok..I was only two when Goldwater ran in 64..I haven't really studied the GOP nomination race then..but Goldwater or any GOPer did not have much of a chance that year because of the tragic hangover of JFK assassination the year before..as for Reagan, he is remembered fondly because of his landslide victories and truly being a great President. But in the late 70's..Reagan had few friends in the GOPe..they were furious with him for running against sitting President Ford in the primaries and perhaps weakening him..sadly a lot of the GOPe bought into the myth that Reagan was too old and just a B-movie actor who would start WWIII by nuking the Commies..fortunately, Reagan overcame them, the liberal media (remember, no talk radio, Fox news or internet) to win so handily. Also, it's not just the GOP where that doesn't always work. Just 8 years ago Hillary had all the endorsements, even the black endorsements, all the workers etc. And look what happened there!
The media tried to build up Gov. Scranton of Pennsylvania but that didn't get very far...he was an unknown and just a "not Goldwater" vote. National Review had a joke which ran: "What do you think of Scranton?" "I don't know--I've never been there."