Note that when FM radio first appeared (c.1946, IIRC...) its primary competition/comparison was *AM* radio! In fact, as I recall, much of the programming on early FM stations was classical music...mainly because its "fans" were more likely to appreciate FM's much-improved frequency/bandwidth...!
In the fifties (my youth...!), most young people listened to AM, and usually to the "Top 20" rock'n'roll hits. Thus, there was very little interest in "high fidelity" reproduction...and AM (they didn't yet have FM radio in cars...!) served the purpose quite well. There WERE "hi-fi nuts"...all adults, though, and mostly more interested in bragging about their systems than listening to them!
In the sixties, there was much more interest in decent-quality audio... and, as well, FM stations started playing rock music (and usually full-length versions of hits,too...!) Most young people had reasonable- quality component-stereo setups, also...lots of Dual turntables fed into decent-quality systems. The old "record players" were either tossed or given to younger siblings...!
These days, for the younger crowd the idea seems to be VOLUME rather than quality...doesn't have to be hi-fi...but it DOES have to be at earth-shaking levels (especially in vehicles)! So, if one can download an MP3 for $0.00, rather than buying a CD for a lot more... well, "free" wins out!
Steven C. Barr