What we do see is a world that's paranoid of nuclear war, therefore greater use of tubes is implemented and technologies that survived the war have tubes.
Now. As for beeps and other synthesized sounds- they are present in game via robots. So even if transistors weren't present in any capacity, those sounds still happened in the FO universe. All it would take is a musician to make use of them.
Lastly, as for older music being basic... classical music, big band swing and other forms of jazz are much more complex than 12 bar blues, which much of today's music is based on. If anything the vast majority of popular music today is much less complicated. It's highly repetitive and short.