High res audio is largely a marketing excercise designed to extract money from the fans. It is demonstrably unnecessary for replay.
In the days of analog consumers had two choices. Monophonic, and stereo records (not counting outliers such as open reel or the later cassettes, but those were either mono or stereo). Now, in addition to hi-rez, record companies offer remixes. The hi-rez angle is, I agree, simple marketing. But one can find added value in remixes, albeit not in the usual sense of offering anything 'better' than the original.
To cite an example, Brian Wilson mixed many of his multi-track recordings to mono. From a marketing and sales angle, it was not the best decision. To counter, Capitol pressed them using an electronic process they called Duophonic (which they then sold for one dollar more). It wasn't just the Beach Boys, but a lot of the old monophonic Capitol catalog (such as Frank Sinatra) could be purchased in Duophonic. How did it sound? In those days, if you didn't like the effect, you could switch your receiver to mono and blend the channels (they all came with that function, often missing in today's gear). It was not ideal, but you at least had the option to do it. Or just save a dollar and buy the mono record.
The worst offenders were probably 'budget' classical labels. For instance, Vox screwed up many wonderful monophonic recordings in an attempt to opportunistically market stereo. In that respect, i.e., the money grubbing angle, it was the same then as you see it now, with hi-rez. The difference being that Duophonic and the other 'reprocessed for stereo' records actually gave you something that sounded different.
The added value part of what you can buy today is more important than whatever hi-rez does or doesn't offer. Capitol released all the group's early mono records in true stereo (those recorded from late 1964 through 1967--coinciding with the time Brian started to go south, mentally, and the group subsequently assuming joint production). The record company used the original four track open reel session tapes that had been archived in a closet somewhere, for some or another reason. It is now possible to actually hear Brian's intricate studio work (provided by top tier LA session musicians). So from that perspective there is a definite added value to the new product. It is an open question whether these later remixes are aesthetically 'better' than the original mono. But that is a different question. I'd say that in general the answer is no, however YMMV.
Occasionally I receive 'junk' email from a hi-rez outfit offering an opportunity to download many fifties and sixties mono recordings, now remastered in 192/24. The only thing required is more money and additional bandwidth. I ask myself, will a 192/24 mono remaster of
Surfin' sound better than the original do-nut hole Candix 45 rpm? Does the remaster utilize all those extra digits in an important way? To tell you the truth, I'm not even sure the original was recorded in stereo, but if it was, it likely had vocals on one channel, and instruments on the other. My money is on the original 45, for aural authenticity.
Very funny anecdote from Carl Wilson, that keeps 'old catalog' hi-rez remastering in perspective:
We didn't know anything about the sounds or how a record was made. We just lucked out. My dad knew a publisher and we went to a studio and we made a record. And the way it sounded was the way it sounded.
All that said, the fidelity of Brian's mid '60s multitrack session tapes demonstrates remarkable high fidelity (compare the different 'takes' made during the
Pet Sounds rehearsals). You hear the original 'studio ambiance' (reverb etc) that is lost within his final monophonic mixdown.
Since we like pictures, below is Wilson in his better days, with a distinctly non hi-rez tape machine, and associated amplifier. Proving that making high quality recordings doesn't require super high tech over the top gear with hundreds of sliders, effects plug-ins, massive CPU power, and zero distortion electronics. You just have to know what you are doing.