If compressing makes quiet passages easier to hear, what is the disadvantage?
Part of the power and emotion in music is attributable to dynamic range. It’s why composers include such notation in their scores. The nuance of a solo oboe and the thwack of a tympani are two different things. Yet a tympani can also be used to create a gentle roll, which is distinguished (in part) from the thwack by volume difference - dynamic range.
... what is the advantage of not being able to hear quieter passages in uncompressed material?
None at all! That’s why we have compression. But you can hear much deeper into a wide DR recording if you’re listening in a quiet room than you can in a noisy subway car.
Can it be that complaints about the sound are more due to something else than to the dynamic range?Sometimes. There are many ways to ruin a recording. Overuse of compression is just one of them.