I like the blight/taint as something natural in the sense of how evil is part of human nature too. We all hear two songs, a good one and an evil one. The weaker we are (emotionally) the louder the evil song becomes, the easier we are manipulated.
A large group of people develops a kind of hive mind. That's why mass hysteria is so dangerous. The individual is submerged in the group, becomes part of one huge body with one collective purpose. You are being pulled along. It's like a spell.
Groups amplify emotions. If the emotion is destructive, the damage can be immense. Groups can have spontaneous chaotic reactions or respond to a leader's calculated stimulation.
However, it seems that the taint originated somewhere, it's not part of everyone. It might still symbolize human sin like in the Chantry tale. A divine punishment, an amplified version of human greed and destruction. But perhaps the ones who sinned were the elven gods.
So the gods themselves (whether they really are gods or not doesn't matter) corrupted themselves somehow by their actions. I don't think slavery is their sin. The taint must have a physical origin, not a philosophical. I like the theories about it being some kind of magic the gods played with without understanding it, unleashing the taint by accident. Or more sinister, and my favorite theory, a biological weapon. Abelas said the elves were at war and destroyed themselves. Either this happened after the gods were locked away or it was the reason they were locked away. If the gods were at war, one of them might have tried to use some kind of new magical weapon to gain power over the others. Fen'Harel then locked them away and sent the tainted Arlathan into the fade to contain the corruption. Then the magisters arrived at the black city and brought the taint into the world after all...
I support the idea that the old gods lured the magisters into the black city so they would unleash the taint and create an army of darkspawn to help them free themselves from their prison. I like the theory that the old gods are the elven gods. The astrariums seem to hint at it, but that would mean most of the elven gods are dead now, right? It could explain why Solas is in such a hurry. He doesn't want them all to die. And why Mythal sent Morrigan to do the ritual. To save her fellow god...
If the old gods are the elven gods, it would probably mean that they are corrupted. If not by the taint itself, then at least corrupted in the sense that they are so filled with hatred that they would destroy the world just to have their revenge.