Where did 'trauma' come from and why do I hate it?
It seems to belittle people's experiences. It describes in a single word as if all tragic events that happen in a person's life can be explained away in a single word. Or, that people can say "I have trauma" - as if the severity is the same.
As a writing device, it seems pointless, at least if it happened in the past. And perhaps lazy, since you want to ad depth to a character without the time and trouble of writing dialogue or story.