Music don´t sound as usual

The key to the problem is that, in making the soft parts of a track louder (in the process making the entire track loud), you lose detail in the song: The difference between what's supposed to be loud and what's supposed to be soft becomes less and less. The result is that, sure, the soft parts of a song are nice and loud, but big noises like drum beats become muffled and fuzzy. But consumers often subconsciously equate loudness with quality, and thus, record producers pump up the volume. Anything to make a buck.
The bigger problem is that this is all unnecessary. Stereo equipment is more powerful today than ever, and last time I checked, every piece of music hardware had a volume knob.