It wasn’t all that long ago that most people will have listened to most of their music on a traditional ‘hi-fi’, though how ‘hi’ the ‘fi’ was is, of course, another matter. Most living rooms in the UK will have had some sort of micro system, or similar.
The only other form of listening which large numbers of people will have used will have been the car stereo, or a transistor radio, maybe in the work place.
Boomboxes were very popular. But the Walkman in 1979 created the mobile hifi market. Walkman morphed into Discman, then MP3 players, then iPods, then iPhones. So it's been 44 years since mobile devices have been a primary means of music listening for many people.
When I was in college in the early 1980's many of the boys had a modest component stereo, with a ~30W receiver, turntable, and a pair of small acoustic suspension bookshelf speakers. A few had bigger more impressive systems. Very few of the girls had a component system, preferring a compact hifi system.
I suspect most music these days will be heard from either earbuds, or Sonos-style speakers.
I wonder if this, in turn, has any impact on how it’s mixed and mastered.
None of my 3 sons has a hifi system. Two have small rechargeable bluetooth speakers, and one has a small Edifier R1280 speaker pair. This seems typical for the 20-somethings today.
I was amused when one young reviewer described the
Edifier S2000 Pro (small self-powered monitor speakers with 5.5" woofers) as "huge", "massive", "real units". So it must seem for someone who has never used anything bigger than a portable bluetooth speaker!
That said these small speakers often sound better than those compact hifis did back in the day, thanks to class-D amplification, DSP, and modern speaker technology. And there is no comparison between today's premium earbuds and the tinny sound from the Walkman type headphones.
Given that most people today listen on equipment that is much superior to what
most people listened to in the heyday of hifi, I doubt that trends in music production reflect the playback equipment of the end user. I think the abundance of new technologies and techniques available to the recording engineer or producer is the driving factor. The possibilities for manipulation and synthesis of sound were not imagined 40 or 50 years ago.