Well, the OBVIOUS answer to the original question is, “Of COURSE there were people who hated the Beatles in 1964.” You’re never going to have unanimity of opinion on any subject. There were elderly folks who hated rock and roll in general, and thought the Beatles’ music was just noise. There were jazz and classical music lovers who thought the Beatles’ music was puerile and unsophisticated. Even at the height of Beatlemania, there were millions of people who disliked the band.
That goes without saying. Not everybody liked Bing Crosby in the 1930s, not everybody liked Sinatra, and not everybody liked Elvis in the 1950s. EVERY artist, no matter how popular, has some detractors.
But I think the OP is getting at something different. Today, it seems that bands or artists who become popular almost always inspire a vicious, vulgar, angry, and IMMEDIATE backlash. There were people who hated the Monkees in 1965, just as there are people who hate 'N Sync today. But back in 1965, Monkee haters simply ignored the Monkees. When a Monkees song came on the radio, or the Monkees sitcom was on TV, people simply changed stations. But today, 'N Sync haters don’t ignore 'N Sync- they curse them and mock them at every opportunity. They create “I HATE 'N SYNC” web sites. Their hatred seems a little more venomous, and a little more obsessive.
Similarly, people who hate Brittney Spears today are a LOT more vocal and a lot meaner than people who hated, say, Lesley Gore in the 1960s. People who hate the Backstreet Boys are a LOT more vicious than people who disliked, say, the Partridge Family in the 1970s.
Why is this? I’d guess that it’s mainly because of the way the media have changed over the last few decades. In the 1960s, “the media” weren’t so omnipresent. Even the most overexposed, overhyped celebrities were fairly easy to avoid. In 1964, if you hated the Beatles, it was fairly easy to avoid them. They weren’t on American TV very often (an occasional performance on the Ed Sullivan show was about it), and there were MANY radio formats that didnt feature Beatles songs. So, in 1964, if you hated the Beatles, you were in luck: you almost never had to see or hear them. If you were an older TV viewer or radio listener, there were plenty of entertainment options available to you.
Today, however, “the media” are omnipresent, and they’re increasingly tailored to the same market: young, affluent white people. As a result, it’s been a lot harder for me to avoid Brittney Spears than it was for my grandmother to avoid the Beatles. She’s on TV, she’s in the movies, she’s on the radio, she’s in commercials… and if you don’t like her, it starts to feel as if she’s being jammed down your throat.
And THAT, I think, is why popular artists today face hostility that popular artists of the 1960s didn’t. People start to feel like they’re being bombarded, and they resent it. In the 1960s, nobody thought, “Damn that Diana Ross… I just can’t get away from her!” But LOTS of people feel that way about current boy bands and teen-sexpot singers.