A reason for the better sounding recordings of the 50's and 60's may be that there is a lot less of all the little "problems" you mention in rant.
That simply isn't something that's supported by fact.
Equipment in the '50s and '60s was marked by its high THD, noise, microphonics, and nascent electrical engineering. Signal chains, instead of having loads of DB25 interconnects, had multiple generation losses on tape decks with, by today's standards, abhorrent specs. Almost every piece of equipment in the chain was a tube device that added multiple odd and even-order harmonics (which is actually perceived as pleasing to the ear, although it is, by definition, distortion).
The entire philosophy of '80s recording and engineering was to clean up the signal path of the '50s-'70s, which was considered to be extremely low fidelity.