The late 13th century musical theorist Johannes de Grocheo said motets were not to be performed for the common man, as they were not able to understand the subtleties portrayed. Bach wrote his motets mostly for funerals. So these are funeral songs for people with a refined religious taste.
With the motet, Bach was rather late. They were part of a vocal tradition that went back deep into the Middle Ages, but did not extend very far after Bach. Sure, more modern composers (Arvo Pärt) tried their hand at creating them, but in general, after Bach, the fun was over with the motet.
I haven’t heard this record in a long time and I remember it always sounded like a wall of sound, but then with choir. Something definitely has changed, because I can now hear a lot more detail. Now I think this is really good recording, with lots of detail and depth.