I found this passage interesting:
What has changed is how the chords are spliced into melodies. In the
1950s many of the less common chords would chime close to one another in
the melodic progression. More recently, they have tended to be
separated by the more pedestrian chords, leading to a loss of some of
the more unusual transitions. Timbre, lent by instrument types and
recording techniques, similarly shows signs of narrowing, after peaking
in the mid-60s, a phenomenon Dr Serrą attributes to experimentation with
electric-guitar sounds by Jimi Hendrix and the like.
I believe that pop music today is very much influenced by guitar music and guitar thinking.
--
Louigi Verona
http://www.louigiverona.ru/