If all you listen to is the radio, sure. However in the broader sense of music being created, this is patently false. There are more genres and subgenres of music than ever before, experimentation and synthesis techniques weaving together ever more intricate and sophisticated timbres.

Movies are a better example of a medium getting bland, but there is a material reason for that; production costs vs return on investment leading to less riskier films being made.

Music doesn't suffer from that same problem, in fact 'good' music can be made for nothing except the composer's time.