Um, yes it actually does have to be that loud sometimes. Some venues have taken your advice and it's lead to lame events where some people can barely hear the music in certain parts of the venue and there's no punch, even right next to the speakers.

It's even noticeable, because a lot of venues have this really annoying practice of turning the system way down for the openers, thus hamstringing their set, and making the headliner look that much better. Believe me, artists can look really silly playing quiet elevator music while we wait for the real act. (what a fing rip if you paid $50-100+ on a ticket).

Loudness is a component to musical enjoyment. Very much like the carbonation, acid, and alcohol we add to drinks to make them fun. In those cases too, our bodies can be damaged too. Often times what's fun, hurts us. I do think it's stupid if they don't have hearing protection available.