Engineering and production techniques are just so different now. If you liked the sound of "back then" (whenever that was), then you might be turned off by what's going on now. If you like what's going on now, you might be turned off by what was going on "back then".
There are certain differences that are almost inarguable, even if they don't necessarily imply a quality issue. Analog vs digital. A few tracks vs a near-infinite number of tracks. Personally, I think digital sounds fine when used properly. I think certain plugins sound fine. As far as the near-infinite number of tracks go, that's an interesting topic. "Back in the day" limited resources forced the artists and engineers and producers to make quick calls in the heat of the moment -- "should we erase this and try again or just keep it?". There is some beauty in that. It definitely unclogs the mixing process, BUT there is risk that the best take might have been erased. Artists understood this and learned to compromise. Now, it's almost impossible to mix some songs because there are just too many choices to weed through. (At least it's hard for me.)
The other thing that I don't hear as much chatter about is signal chain choice along with things like mic placement. Multiple flavors abound. For awhile there was an obsession over a studio having a dozen or more fantastic mic preamps, EQs and compressors, multiple copies of a dozen great microphones, etc. Ironically, a huge number of great records have been made by using the console preamps almost exclusively, especially if they are classics like Neves and APIs and even SSLs (hey to Paul W). The same goes for relying on a couple of great compressors and maybe one or two great reverb units. Shit, we've all heard HUGE classic hits that used a Shure SM57 for almost everything, a mic that is still available for $90. That philosophy can be carried forward into the modern world, even in the mix regime. I rely almost exclusively on two EQs -- one that comes with my DAW (Reaper), and one that emulates a Neve 1073 extremely well. I use maybe two compressor plugins. Two reverbs. I just can't stand a shootout of a dozen plugins when I'm trying to mix a fucking song, AND I'm a nobody.
Back to then vs now -- a huge number of classic records were recorded mostly live in the studio. There can be an organic vibe that results, and microphone bleed can actually help "glue" the sound. Plenty of current artists still try to work that way; for instance, Wilco. They are less concerned with "mistakes" making it to the mix than they are with art, and I think it works, at least for them.
Last thing: we were listening to a Teddy Swims song in the car today. I pointed out to my wife the overreliance on autotune, and said I felt he is a good enough singer not to need it. THEN it hit part of the song where he started reaching up into his higher register and it was clearly NOT autotuned, and it sounded fantastic. Two lines later, he's back in his mid-voice and the pitches are not only perfect but robotic. Just fucking infuriating.
So, a lot of words with probably very little insight. SOP for me.