When you hit 40 you start to see in real time how valuable those old songs are. Your friends and other people in your age group hate the new music so they only listen to music from when they were young. All of the commercials play music you thought would never be used in a commercial. Walking through the grocery store or waiting in an elevator you start to bop your head because one of your favorite songs from high school is now elevator music. A popular song has a lot of long tail value, sometimes you have to wait a generation to start to see the returns.

"Your friends and other people in your age group hate the new music so they only listen to music from when they were young."

Young people hate a lot of music made these days and listen to older music. It's not just a 'when I was young' thing anymore.

There's something very profound that comes from artists who make music, as opposed to a producer who makes some licks, a mediocre singer who belts it out, and a label that brands it.

When the brand/hype/marketing of the 'current flavour' dies down, what is left?

Music older than 4 years has to compete on its own merits, and most of it is forgotten, the better stuff hangs around.

Because music is ever more produced and less created, a lot of the stock today just stand the test of time.

When I was young you'd hear 50's music in the grocery store. Now you hear 80's music. But I think in 30 years we're still going to hear a lot of 80's music (and 60's, 70's and other eras) but the ratio of 'recently contemporary' to older music will be a lot lower.

You will always have some young people who like an older sound. But no, those songs that you think people will hate will be called classics in 10 years time. As a former DJ I have seen that cycle over and over again. When I go to grocery stores I hear mostly 90s music. Most of the commercials I see have 90s or 80s music in it. And when 20 year olds get in their 40s it wil be the same pattern.

They always did. Young people like to be contrarian.

"Now you hear 80's music."

I heard "Christmas" music in the grocery store that was some traditional song but done in a 90's grunge style.

But it does seem like you have to go out and find music from 2000-2015 these days.

See also Stranger Things, Guardians of the Galaxy (I and II), Captain America, etc.

There was a "classic rock" radio station playing in the store where I get my morning coffee, and it was playing the same songs as 25 years ago, from the 70s or 80s. By now shouldn't they be playing music from 1995-2005?

And yet when you see a car commercial they use an old song.

You’re not accounting for the value of nostalgia and cultural significance.

In many cases, old songs are used precisely because they are cheaper to license.

Old songs have greater surface. Many more people have heard it over something popular today which 20% might have heard of. New music is usually much cheaper. Even within the same artist. Would you lic. Bieber's Baby, baby O or something new. More extreme example would you lic gangnam style or anything newer by that artist?

Not really its why TV shows have to be careful with the budget for licences - though this can work very well "sinner Man" as used in an episode of Person of interest.

Only when the car is advertised to boomers. Fords new electrified cars commercial pumps techno.

And they'll keep pumping that same techno in 5 years when they want people to get Gen 2 electric cars

It's not just than new ones are pumped out, it's that people lose interest and move on. Taylor Swift will do better than someone less popular, but people still listen to "Blank Space" more than "Love Story." Going back further, kids these days are less likely to know the Beatles.