That's not how it used to be.
Motown, The Beatles, Nirvana, etc. . . were not targeting children.
It's something that has become more prevalent as time has gone on.
LolWut
The Rolling Stones, The beach boys, The beatles, The monkeez all of those
of 1950's/1960's Rock N' Roll bands were primarily targeting young adults/teens.
This is without mentioning that they were young people themselves when making
that music.
That's also who Berry Gordy and his loads of producers and artists were targeting.
The young Black/White dollar.
Marvin ? Stevie ? The Temptations ? The Supremes ? Jackie Wilson ? And all of the other artists
on these labels and other labels with similar goals WERE NOT targeting adults.
It's BEEN prevalent because they (Labels and musicians...) recognized this EARLY ON.
"Young people" probably recognized the brilliance in Mozart and Beethoven but they
didn't dance to it in the 1940's/1930's because Jazz was tearing up the charts (Swing was THE dance
music then....).
"Young People" probably saw the brilliance of Bebop artists but they didn't dance to it
because by then Jazz was on it's way to being replaced by Rock music as a dominant force
in (Popular) American music.
"Young people" still do think Rock is cool but for the most part Hip Hop has carved out it's
on niche in the past 30-40 years and well people still like dancing to it
I say this without mention Funk/Soul/Disco all of which heavily focus on common time
and being danceable.
Pretty much all of these art forms changed a great deal as they moved away from
being "Music you dance too" to "Music you listen intently too".
Usually once that happens the young people find SOMETHING ELSE, there's a reason
Electronic Dance Music has and still does have a hold on the public and probably will
for the foreseeable future.
"Popular Music " WAS and STILL IS in some ways seen as disposable, it's only now that
decades have past that people realize the popular song has staying power and can
be considered great like the "Art music" of European Masters (Beethoven, Brahms, Bach etc.)