Fantasy tropes have little to do with it. Here's basically the same rant in relation to US history (warning: some colorful language is possible):
Colorful language form George Carlin! How is that possible?!?
The discussion is also not new. You're bringing it up in 2013. The rant above is from 1990.
Interestingly, I used to agree with Mr. Carlin on this one. Now, I don't fully agree. Unlike "battle fatigue" and "operational exhaustion", PTSD is not softening language. It is actually characterizing the issue more correctly. While the world originally only thought of this in terms of combat veterans, when they changed the language, they started to realize that PTSD was not strictly a disorder arising from combat. It can occur to anyone who has been under sufficient stress or undergone trauma. So, for example, abuse victims are now recognized as having much the same problems, allowing them to get more appropriate treatment than they used to.
So, the words we use to speak of a thing do matter sometimes.