Answer by taking a quote from the following article:

Sgt. Pepper's Lonely Hearts Club Band is the eighth studio album by English rock band the Beatles. Released on 26 May 1967 in the United Kingdom and 2 June 1967 in the United States, it was an immediate commercial and critical success, spending 27 weeks at the top of the UK albums chart and 15 weeks at number one in the US. On release, the album was lauded by the vast majority of critics for its innovations in music production, songwriting and graphic design, for bridging a cultural divide between popular music and high art, and for providing a musical representation of its generation and the contemporary counterculture.

By 1966, the Beatles had grown weary of live performance. In John Lennon's opinion, they could "send out four waxworks ... and that would satisfy the crowds. Beatles concerts are nothing to do with music anymore. They're just bloody tribal rites." In June that year, two days after finishing the album Revolver, the group set off for a tour that started in Germany. While in Hamburg they received an anonymous telegram stating: "Do not go to Tokyo. Your life is in danger". The threat was taken seriously in light of the controversy surrounding the tour among Japan's religious and conservative groups, with particular opposition to the Beatles' planned performances at the sacred Nippon Budokan arena. As an added precaution, 35,000 police were mobilised and tasked with protecting the group, who were transported from hotels to concert venues in armoured vehicles. The polite and restrained Japanese audiences shocked the band, because the absence of screaming fans allowed them to hear how poor their live performances had become. By the time that they arrived in the Philippines, where they were threatened and manhandled by its citizens for not visiting the First Lady Imelda Marcos, the group had grown unhappy with their manager, Brian Epstein, for insisting on what they regarded as an exhausting and demoralising itinerary.  After the Beatles' return to London, George Harrison replied to a question about their long-term plans: "We'll take a couple of weeks to recuperate before we go and get beaten up by the Americans." His comments proved prophetic, as soon afterwards Lennon's remarks about the Beatles being "more popular than Jesus" embroiled the band in controversy and protest in America's Bible Belt. A public apology eased tensions, but a miserable US tour in August that was marked by half-filled stadiums and subpar performances proved to be their last. The author Nicholas Schaffner writes:  To the Beatles, playing such concerts had become a charade so remote from the new directions they were pursuing that not a single tune was attempted from the just-released Revolver LP, whose arrangements were for the most part impossible to reproduce with the limitations imposed by their two-guitars-bass-and-drums stage lineup.  Upon the Beatles' return to England, rumours began to circulate that they had decided to break up. Harrison informed Epstein that he was leaving the band, but was persuaded to stay on the assurance that there would be no more tours. The group took a three-month break, during which they focused on individual interests. Harrison travelled to India for six weeks to study the sitar under the instruction of Ravi Shankar and develop his interest in Hindu philosophy. Having been the last of the Beatles to concede that their live performances had become futile, Paul McCartney collaborated with Beatles producer George Martin on the soundtrack for the film The Family Way. Lennon acted in the film How I Won the War and attended art showings, such as one at the Indica Gallery where he met his future wife Yoko Ono. Ringo Starr used the break to spend time with his wife Maureen and son Zak.  In November 1966, during a return flight to London from Kenya, where he had been on holiday with Beatles tour manager Mal Evans, McCartney had an idea for a song that eventually formed the impetus of the Sgt. Pepper concept. His idea involved an Edwardian-era military band, for which Evans invented a name in the style of contemporary San Francisco-based groups such as Big Brother and the Holding Company and Quicksilver Messenger Service. In February 1967, McCartney suggested that the Beatles should record an entire album that would represent a performance by the fictional band. This alter ego group would give them the freedom to experiment musically. He explained: "I thought, let's not be ourselves. Let's develop alter egos." Martin remembered:  "Sergeant Pepper" itself didn't appear until halfway through making the album. It was Paul's song, just an ordinary rock number ... but when we had finished it, Paul said, "Why don't we make the album as though the Pepper band really existed, as though Sergeant Pepper was making the record? We'll dub in effects and things." I loved the idea, and from that moment on it was as though Pepper had a life of its own.  In 1966, the American musician and bandleader Brian Wilson's growing interest in the aesthetics of recording and his admiration for both record producer Phil Spector's Wall of Sound and the Beatles' album Rubber Soul resulted in the Beach Boys' Pet Sounds LP, which demonstrated his production expertise and his mastery of composition and arrangement. The author Thomas MacFarlane credits the release with influencing many musicians of the time, with McCartney in particular singing its praises and drawing inspiration to "expand the focus of the Beatles' work with sounds and textures not usually associated with popular music". McCartney thought that his constant playing of the album made it difficult for Lennon to "escape the influence", adding: "It's very cleverly done ... so we were inspired by it and nicked a few ideas." Martin stated: "Without Pet Sounds, Sgt. Pepper never would have happened ... Pepper was an attempt to equal Pet Sounds."  Freak Out! by the Mothers of Invention has also been cited as having influenced Sgt. Pepper. According to the author Philip Norman, during the Sgt. Pepper recording sessions McCartney repeatedly stated: "This is our Freak Out!" The music journalist Chet Flippo states that McCartney was inspired to record a concept album after hearing Freak Out!, considered the first rock concept album.  Sgt. Pepper, according to American musicologist Allan F. Moore, is composed mainly of rock and pop music, while Michael Hannan and Naphtali Wagner both believed it is an album of various genres; Hannan said it features "a broad variety of musical and theatrical genres". According to Hannan and Wagner, the music incorporates the stylistic influences of rock and roll, vaudeville, big band, piano jazz, blues, chamber, circus, music hall, avant-garde, and Western and Indian classical music. Wagner felt the album's music reconciles the "diametrically opposed aesthetic ideals" of classical and psychedelia, achieving a "psycheclassical synthesis" of the two forms. Musicologist John Covach describes Sgt. Pepper as "proto-progressive".  Concerns that some of the lyrics in Sgt. Pepper refer to recreational drug use led to the BBC banning several songs from British radio, such as "A Day in the Life" because of the phrase "I'd love to turn you on", with the BBC claiming that it could "encourage a permissive attitude towards drug-taking." Although Lennon and McCartney denied any drug-related interpretation of the song at the time, McCartney later suggested that the line was deliberately written to ambiguously refer to either illicit drugs or sexual activity. The meaning of "Lucy in the Sky with Diamonds" became the subject of speculation, as many believed that the song's title was code for the hallucinogenic drug LSD. The BBC banned the track on those grounds. They also banned "Being for the Benefit of Mr. Kite!" because of the lyric, which mentions "Henry the Horse", a phrase that contains two common slang terms for heroin. Fans speculated that Henry the Horse was a drug dealer and "Fixing a Hole" was a reference to heroin use. Others noted lyrics such as "I get high" from "With a Little Help from My Friends", "take some tea" - slang for cannabis use - from "Lovely Rita" and "digging the weeds" from "When I'm Sixty-Four".  The author Sheila Whiteley attributes Sgt. Pepper's underlying philosophy not only to the drug culture, but also to metaphysics and the non-violent approach of the flower power movement. The musicologist Oliver Julien views the album as an embodiment of "the social, the musical, and more generally, the cultural changes of the 1960s". The American psychologist and counterculture figure Timothy Leary contends that the LP "gave a voice to the feeling that the old ways were over ... it came along at the right time" and stressed the need for cultural change based on a peaceful agenda. The album's primary value, according to Moore, is its ability to "capture, more vividly than almost anything contemporaneous, its own time and place". Whiteley agrees, crediting the album with "provid[ing] a historical snapshot of England during the run-up to the Summer of Love". Several scholars have applied a hermeneutic strategy to their analysis of Sgt. Pepper's lyrics, identifying loss of innocence and the dangers of overindulgence in fantasies or illusions as the most prominent themes.

What was important about the lyrics?
Concerns that some of the lyrics in Sgt. Pepper refer to recreational drug use led to the BBC banning several songs from British radio,