Your title, & therefore premise, is inaccurate; you specify 'art' yet only talk about comics not art or, more correctly in the context of your argument, literature. In that context & for that reason I'll presume to bracket comics in the same artistic branch as literary narrative:erttheking said:Why do so many people think that in order to be mature, art has to be dark and depressing?
Regardless of who you read, the inevitable consensus amongst academics, philosophers, & authors alike is that there are certain essential elements of a narrative. The specific number of these elements stated may vary depending on whose view you're paying attention to e.g. Aristotle's Poetics agrees in principle with Sternberg's Universals of Narrative, but Aristotle sub-divides these features & elements differently, but their qualities are identical - the mechanics of the narrative's delivery remain the same. Essentially the main narrative components are:
1. Plot (the events which occur in the story).
2. Setting.
3. Characterisation (typically physical & ethical, as well as behavioural).
4. Narrative style (typically third or first person).
5. Conflict (the reason for the story).
6. Denouement (resolution or conclusion of events).
In any literary work you're likely to read, from The Iliad to Beowulf (the poem, not Neil Gaiman's racist cartoon), any play you see from Hamlet to Rosencrantz & Guildenstern are Dead, or any film you watch from The Maltese Falcon to Star Wars those six components will be there (there are exceptions, but they're extremely rare). They're the mechanisms which allow the narrative to unfold, you will see them if you know to look for them, & conflict is dark. It has to be dark in order to fulfil its function, it's supposed to be dark, that's how it works, it's conflict! More than any other element of the narrative, conflict is the most influential & the most important, because it's that conflict & its denouement which carries the weight of the rest of the narrative. As such it's quite normal for the darkness of the conflict to influence other narrative components e.g. the Trojan War in The Iliad provides much of the plot, the entirety of the setting, & all of the behavioural characterisation; much the same applies to Hamlet, substituting the siege of Troy for the murder of Hamlet's father, obviously. As the always excellent Tom Stoppard observes about narrative in Rosencrantz & Guildenstern are Dead:
"we can do you blood and love without the rhetoric, and we can do you blood and rhetoric without the love, and we can do you all three concurrent or consecutive. But we can't give you love and rhetoric without the blood. Blood is compulsory. They're all blood, you see."
To say that dark narrative characteristics are a modern trend is fatuous. The oldest known narrative is the epic poem of Gilgamesh, well over four thousand years old (the tablets are in the British Museum & have been dated), in which you have immortals & gods battling it out, & particularly dark events unfolding. Even genocide in one instance, that's where the Bible stole its Flood story from all those hundreds of years later.
Literary narrative requires conflict which, by its very nature is dark. No darkness no narrative, no narrative no literature, no literature no art. It's not new, in fact 'dark & depressing' is very very very old, it's as old as the oldest story ever.