Complaining is an activity that is generally criticized, labeled as useless and annoying.
There are many other futile occupations certainly not more pleasant (shouting at the stadium, getting angry while driving, Christmas spirit, serenades...) they don't draw criticism with the same intensity though.
So this fundamental human activity took another road to finally be expressed. It has been codified into poems, songs and rituals, because sometimes there’s just nothing you can do but wait and survive, and those could work good to fill the time (and empty the soul) while waiting for a better time to come.
Image: Martha Graham - Lamentation