Quote johnny h:
Studios have changed so much since those days, and the skills of those engineers are pretty much lost forever. Getting that natural dirt and crunch back into the recordings without sounding harsh is a very difficult skill.
I don't think they are lost -- plenty of engineers and producers are still very much aware of how it was done and why it worked.
The reason it's not done that way anymore is because few people have the confidence to work that way. They don't want to record vocals in a few superb takes, they want or expect to comp a vocal track from dozens of average takes, and to autotune any performance faux pas.
They don't want to record the band as an ensemble and use the inherent spill in the small studio as an integral part of the sound because that means unimpressive and under-rehearsed performances can't be fixed through countless overdubs and editing.
In short, most people are too comfortable and too lazy thanks to the techniques associated with modern DAW production. The fashion and style today is generally for uber-production. It was done differently in the Motown era, and could still be done if the desire and drive was there.
Technical Editor, Sound On Sound