Broadly speaking, the average listener to the Beatles in the prime of Beatlemania in 1963 (in the UK) or in 1964 (in the US) were people in the demographic prime of the baby boom - someone born in 1950 was 13 or 14 when Beatlemania hit, and 17 or 18 when the Beatles prominently became experimental and psychedelic. This difference in ages does matter; the things you like when you're 13 or 14 often seem a bit cringey and passe by the time you're 17 and 18, and part of the Beatles' genius was that their music fit the journey that their fans were on, as they became more aware of the culture and society around them. So the 13 year old who loved 'She Loves You' in 1963 with a youthful enthusiasm very often became a 17 year old who loved a much more serious and artistic song like 'A Day in The Life' in 1967, simply because by the time you're 17, you might have gravitated towards music with more 'meaning', as they perceived it - even if they still reacted to 'A Day In The Life' with a kind of youthful enthusiasm.

However, while that was a very common experience, it wasn't universal. Very often, after the height of Beatlemania faded away, the fans just moved on to other interests and pursuits - the Beatles, on their 1966 tour of the US, were quite concerned by some of the stadia they played being ...not as entirely full as they would have liked (though still healthily attended).

In the mid-1960s and late-1960s the Beatles still reliably had hit singles every time they released a song - they still had a large core group of fans who bought everything they put out, basically. But, more often than during the first half of the decade, those songs would sink relatively quickly from the charts once the big fans had bought it. Though not always - 'Hey Jude' in 1968 spent so long at the top of the charts that it began to seem like it would never go away.

And in 1966, the Beatles were confronted with the Monkees, an American confection complete with prime-time sitcom, with strong pop songs written by Brill Building songwriters, and with carefully crafted personae that didn't have to let reality get in the way. For a time during 1966 and 1967, the Monkees were very clearly more popular than the Beatles, and this is not coincidentally during the Beatles' first flush of psychedelia; perhaps it's unsurprising that people who liked the energy of the Beatles and the humour of the Beatles and the strong pop songwriting of the Beatles also liked those things when they heard them in the Monkees. Fans of the Monkees circa 1966 were overall a slightly younger generation of baby boomers than the Beatles fans of 1963, and it is perhaps unsurprising that they might have been a little too young to understand the Beatles' experimentation in the era.

There was also the well-publicised protests and record-burnings of the Beatles especially across the Southern parts of the US, after comments by John Lennon that the Beatles were 'bigger than Jesus' in an interview with an upmarket British newspaper were republished in a teen magazine aimed at teenagers. This comment was taken to be a threat by parts of the evangelical movement of the era, rather than the bemused social commentary that was intended by Lennon in the original interview. There is an element by which the Beatles' experimentation would have sounded...uncomfortable in association with the Beatles were Satanic, etc, and of course many teenagers in the era were quite religious (as many are today) and would have come to believe that it was worth burning the records.

One fascinating view on the Beatles more experimental, psychedelic albums is encapsulated in the Kinks singer-songwriter Ray Davies' contemporaneous review of Revolver in Disc And Music Echo, which is transcribed here. In it, Davies likes 'I'm Only Sleeping' best (probably the most similar song to Davies' songwriting style circa 1966), but his comments on the more experimental tunes on the album are fascinating. For 'Tomorrow Never Knows', Davies says

"Listen to all those crazy sounds! It'll be popular in discotheques. I can imagine they had George Martin tied to a totem pole when they did this!"

In contrast, with 'Good Day Sunshine', Davies says that

"This'll be a giant. It doesn't force itself on you, but it stands out like 'I'm Only Sleeping'. This is back to the real old Beatles. I just don't think the fans like the newer electronic stuff. The Beatles are supposed to be like the boy next door only better."

Presumably 'the newer electronic stuff' refers to stuff like 'Tomorrow Never Knows' that exploits the capacities of the studio; while we associate 'electronic' with synthesisers and drum machines these days, this wasn't yet the case in music discussions in 1966.

However, the other thing that's clear from that Ray Davies review is that, for all that the 'Tomorrow Never Knows' and 'I Am The Walrus' experimentation is so emblematic of their 1966-1967 era, and so lionised today, the Beatles never stopped releasing fairly straightforward pop music. 'I Am The Walrus' was the b-side to 'Hello Goodbye', which is pretty relentlessly pop on the surface. 'Tomorrow Never Knows' shares an album with 'Good Day Sunshine'. Sgt Peppers might have the psychedelia of 'Lucy In The Sky With Diamonds' but it also has more straightforward songs like 'With A Little Help From My Friends'. So if what you wanted from the Beatles was 'sweet love music', you were still, on the whole, going to still be hearing new sweet love music from the Beatles fairly regularly.

That said, don't underestimate how revolutionary the Beatles actually were, sonically, in 1963/1964 - as I discuss here, they really were doing something new at the time; while the lyrics might have been sweet love music, the music was quite innovative. Secondly, as I discuss here and here, it's not going too far to say that Sgt Peppers was an enormous success critically and commercially. As an album it was incredibly successful - Adele successful - while in terms of critical reputation, it was very clearly lauded. In fact a critical review of the album in the New York Times became a big controversy - how dare he criticise our Beatles!