I feel bad for Generation X and The Millennial's

Love those jazz giants and classic rock.  Some good recording and a lot of bad ones.  I like Led Zeplin, but their recording is really not very good.  I think today's music generally is much better recorded.

The reason young people, my kids included, still listen to the great music of the 60s and 70s ("classic rock", singer songwriters, Motown/soul, blues, folk rock, etc., is that nothing has come along to replace it.  Look what's most popular- disposable pop music and rap.  There was a golden age of broadway musicals, and a golden age of jazz, and those are now past- why couldn't this happen to rock?  After the Beatles, everyone wanted to play guitar and start a band; there are not a lot of young Tom Pettys, and Gibson and Fender struggle financially.  Most often if you want to play music now, you do it like Billie Eilish- in your bedroom by yourself with a computer (OK, I know she plays with her brother).  Yes, there are young artists scattered far and wide, (like young Americana artists), but not a mainstream of music in the style we are used to.

My teenage kid watched Squid Game on Netflix and heard "Fly Me to the Moon" and liked it. I played him the original by Frank and now he is a huge Sinatra fan. We watch the Sinatra concerts on blueray and now he is branching out in the genre to other singers and even movies from that era (The Music Man, Guys and Dolls, On the Town, etc). All started because some insane show put a cover version in the soundtrack.

As for any "best era" of anything that just means you are stuck in that era. Nothing wrong with that but fresh stuff is good too. 

Oh man...the drug called nostalgia is running high. It’s pretty telling that the window of "greatest music ever" is limited to one decade of their life. It’s as if Boomers are ashamed of all the great music they grew up listening to as kids and teens. And then decided to fossilize their listening catalog in vinyl amber. That decade had a lot of throw-away pop and rock music and was just as disposable as any other. I’m trying to imagine the Beatles and Stones never bothering to listen to any new music. Imagine they just sat at home and only listened to BBC broadcasts instead of discovering Buddy Holly, Chuck Berry, Robert Johnson, Elmore James, the lyrical disposability of Leib and Stoller, Charlie Parker, Louis Armstrong, Sam Cooke, etc, etc.

I’m a Gen-Xer and I absolutely don’t think that decade was the greatest ever. It was top notch but not the greatest as it implies that nothing great existed before or since. My parents ran a record store in the 70s and 80s and I grew up listening to all genres and time frames of music. I grew up listening to jazz greats from the 40s, 50s and 60s, Delta blues, R&B and rockabilly from the 50s (an era of music for which the artists the OP lists drew all their inspiration from), 60s R&B, 70s progrock and album rock, and then on to influential genres of the late 70s punk, garage, krautrock, funk, disco, industrial and electronic music, reggae, dub, early DJ culture. 80s power pop, new wave, synthpop, 90s industrial, grunge, rap, EDM, etc., etc.

GenX has 40+ years of great music and influential artists that sadly you may never know the aural pleasures of because you stop listening to music made after 1974. I feel bad for anyone who never opens up their listening ears to new genres and artists. The beauty of music is discovering the new. Sure I can put the Drifters or the Cadillacs box set I have on or replay Let It Bleed or Rubber Soul for the 10,000 time and enjoy music from my childhood but I can also put on some New Pornographers, Calexico, Depeche Mode, Broken Social Scene, Radiohead, Winton Marsalis, Anders Osborne, Bjork, or Richard H. Kirk and further my listening experiences.