Why Do RPGs Have This Common Trope? 

It sounds like you've stumbled onto the trope known as "I Just Want to Be Normal." The character receives something or has something inherent to them that they don't want, and they instead desire for normalcy or a return to it than fulfillment of whatever the story demands of them due to their special nature. Desiring the status quo is relatable for the audience, and it's easier to write resistance to the thing than it is to write endearment to the thing. If the writer decides to make them entirely unaffected by the existence of the thing, they usually end up with a Mary Sue of some kind.