I've noticed the same thing with LP's. While LP's are technically inferior to red book CD's, they're often mastered better.
Is there a technical reason why the mastering is so different for the two mediums, CD versus vinyl?
I guess special purpose releases don't usually end up on the radio so they can be mastered for people who actually appreciate music. ;)
More often than not these days, the same compressed master is used for the vinyl. To combat the groove-jumping problem, the overall level is simply dropped.
Thus, people started mastering CDs for loudness.
An alternative idea of mine is simpler. Loud music is considered worse than quiet music (quiet music sounds worse, but loud music still does, and also bothers other people). So, when you need to pick a volume setting for your collection, you bias towards setting it lower, so the really loud ones don't become too loud. Thus, the quieter CDs are annoying because they always sound quiet, whilst the load CDs sound about right, because your volume is much more suitable for them.
As ever this difference can be impossible to detect if the equipment and environment aren't of a sufficient fidelity/quality.
https://www.youtube.com/watch?v=cIQ9IXSUzuM
I think you're right that recording equipment has a long way to go, though; regardless of format I think people can relatively easily distinguish real acoustical instruments from recordings.
What kind of gaps? There are no gaps. Sampled signals perfectly represent the original wave up to half the sampling frequency. Analog systems are inevitably limited in their frequency response as well, so, given the same bandwidth, there would be no difference at all.
In the real world, imperfect A/D and D/A conversions are typically still far less destructive than all the mechanical and electromagnetic sources of noise that affect analog systems. You can't consider one but not the other.