You hit the nail on the head,compressing music is easier but it compromises sound quality. It's not really old music that isn't heavily compressed, a lot of reissues of old music have been significantly altered. A few years back, I measured the crest factor or various CDs in my collection. 80s era rock CDs very consistently had 10-15dB crest factors. By the time I got to more current CDs, those crest factors averaged on the low end (and unfortunately, often times lower) of that scale. If I had a better sampling size, I'd do another test and post the results.
It's purely a matter of convenience, and it's a bad trend IMO. It;s akin to making all the speakers as tiny as you can make them, accuracy be damned. I'm not trying to insult you directly, because I doubt Ihave heard you work, but I can't say I like the trend I have witnessed. It sure makes electonics choices easier, who needs high powered amps now?
The difference lies in how it is mastered and EQ'd. People prefer more bass-heavy, louder music today. That is what most people want to hear, because the advances in speaker technology allow us to listen at much higher levels. Anyone with subs or a decent amount of money in thier car or home system knows what it's like to put in a good old classic rock CD, and crank it only to find that there is no bass and it sounds thin and wimpy compared to today's music. That is how music has "evolved", and I think it sounds better than ever.
True, most people buying most records (read young people) do prefer more bass, and thats why i can understand the bass heavy mixes today. Again, it's all about sales. I think we are going to have to disagree on the technology of today vs yesteryears technology in terms of loudness. One of the more significant trends in audio has been the downsizing of everything speaker related which goes completely against the ability to get loud. Technology has improved in terms of low distortion performance and linearity, but in terms of output/dynamics, no significant improvements have been made aside from creating some horns/wave guides that cut down on early reflections and higher order modes. Some of the old, very large speakers, were capable of tremendously loud volumes without running into compression within the drivers themselves because they were only being fed a watt or two.
You are entitled to your opinion on sound quality, but audiophiles/music lovers will probably not often agree with you.