> People tend to have a warped concept of the history of music. Pachelbel's Canon in D is by no means a complex song and has stood the test of time. Music through out time has also served different purposes. Hell, go back to Ancient Greece, Gregorian chants, and Medieval music. Those various time periods were not generally fully of complexity either. I would argue such times were generally less complex than modern music.

True facts. The fifties and sixties were replete with simple, disposable pop music. "Yummy Yummy Yummy" topped the charts in the late 60s and has, what, three chords in it? What about "Sugar, Sugar" or the Monkees? Staff songwriters and session cats cranked this stuff out by the ton back in the day but people still love to take potshots at modern pop music for being inferior to the oldies in this regard.

The key observation for me is Sturgeon's Revelation: "90% of everything is crud."

My most impressionable years for music were the 70s and 80s. I remember fantastic music from that time... But the fact is, most of what we hear today from that era has been curated for us. We hear the 10% of the 70s and 80s hits that weren't crud. Or maybe even the 1% that was great. If we actually listen to the top twenty-five singles from any month in those two decades, 90% of them would be crud.

I think most people comparing the present to the past are comparing everything today to the 10% of yesterday that wasn't crud.

Complexity is not just variation in chord progression, key, or melody.

Dark Side of the Moon is basically the same chord progression repeated over and over; but with different rhythm, tempo, arrangement for each song. The variation within the scope of the repetition and call backs to various melodic and rhythmic motifs at various points throughout is part of what makes the album such an epic and thematically cohesive listening experience.