I have always felt that popular music is becoming worse and worse. In the 90s I though the 90s music was terrible compared with 80s, 70s, and 60s, and now I think 90s was actually very good relative to today’s music.
It is explained in this video:
The “millennial whoop” is this:
I could not find Andrew Powell-Morse’s original study on lyrics but I found a copy of it here and many articles about it:
BBC newsbeat, The Guardian, The National Post
Read more about Flesch-Kincaid readability index here.