Eric Felten recently wrote in the Wall Street Journal that during the Second World War the federal government imposed a tax on establishments with singing or dancing to live music. Ultimately this was the catalyst of the 50s bebop jazz era that killed big band music entirely. Americans could no longer dance to the music they heard, lest they face a 30% surcharge on meals and drinks. That was a killer for restaurants, and so no dancing was allowed. Furthermore, if vocals accompanied the music, the same surcharge applied, so instrumental music became the norm.
There was nothing inherently bad about instrumental music itself, and for a while it was quite good. But once freed from having to create music with a danceable beat or a singable melody, jazz musicians became wildly experimental. Although some of that experimentation was good, it also led to excesses in which musicians seemed to be trying to jam as many notes into a song as possible with as little rhythm as possible to fulfill some dream of harmonic nirvana.
For a perfect example of what government intervention did to the music industry by 1960, listen to the performance by the Ornette Coleman Double Quartet.