Because they already had a perfectly good female singer/writer/keyboardist at the time.
Totally did forget the Bob Welch version, thanks!
You might be surprised at how musically sophisticated many of those early songs were.
I guess you wouldn’t call him a band, but Bob Dylan went from straight-up acoustic folk music to electric and has continued to evolve over the decades.
And went from activist to absurdist to Jesus freak to devout Jew to… whatever he is now.
Didn’t Jefferson Airplane, a psychadelic rock band from the '60s, de-evolve into Jefferson Starship, that further de-evolved into Starship?
They went from this:
. . . to this:
I mean, there’s a lot of history I’m glossing over, if I’m remembering the fall from Grace the band had.
Tripler
Pun intended.
Ms. Slick has stopped dyeing her hair, and I’ve seen pictures of her with it close-cropped.
https://www.grammy.com/recording-academy/news/grace-slick-talks-painting-expression-madonna
KISS tried the disco thing (with predictable results) and in the 1980s and early 1990s, Rush also turned poppier, with shorter songs, and Geddy Lee reverted more to his natural tenor voice.
I didn’t mean to discount the work of the early Beatles, which I still enjoy to this day. But you can’t deny there’s miles of difference between “I Wanna Hold Your Hand” and, say, “A Day in the Life”.
Blood Sweat and Tears went from a blues-based band with a horn section to starting out their second album with a classical piece. They continued to move away from blues as they became successful.
Donovan started out as a Bob Dylan imitator, then switched to be a psychedelic troubadour.
No. Just…no.
The history you are glossing over is a band that is connected to a previous band by the thinnest of threads. Jefferson Airplane was no more Starship than the Quarrymen were Wings.
A much better singer too.
I don’t know about “biggest”, but Depeche Mode’s Speak and Spell album was a breezy bit of uplifting 80s synth pop with the hit “I Just Can’t Get Enough,” transitioning their sound on their follow-up, still keeping their synth pop bounce, but mixing it with a bit of melancholy, before becoming the mysterious, moody, brooding band that we most associate with Depeche Mode.
Ministry started as a synth pop/alternative/New Wave band and turned into an industrial metal band.
Talking Heads went from a tightly wound four piece minimalist band to an expansive world music influenced band with 10 to 15 people on stage at any given time.
It’s not like Gabriel didn’t also ride that MTV wave of pop hits…
The Cure have done a bit of most things in their time.
TCMF-2F
Beastie Boys from punk to rap/metal fusion.
Ministry from Duran Duran type stuff to industrial metal.
British legends Status Quo started as psychedelic (their first big hit Pictures of Matchstick Men) before soon establishing their better known (in the UK) Hard Rock style (Rocking All Over The World).
Towards the end of their long career they became more and more pop orientated and even put out dance singles comprising of medleys of other - not their own - songs.
TCMF-2L
Bowie. Aladin Sane/Ziggy Stardust. TVC15. Scary Monsters. Serious Moonlight?
And then there’s Neil Young going off the rails with the Shocking Pinks.
They didn’t perform as a punk band under the name Beastie Boys or if they did, they did not achieve any significant level of success as a punk band. From Wikipeidia:
Beastie Boys were formed out of members of experimental hardcore punk band The Young Aborigines in 1978…
After achieving local success with the 1983 comedy hip hop single “Cooky Puss,” Beastie Boys made a full transition to hip hop…