I use them for...I'm not sure how to describe it? I'm writing a 'start of darkness' type thing right now that the readers know going into it will make the character a villain by the end, and I put things in parentheses at the end of each bit lightly sketching out the consequences of whatever happened in that piece, or detailing what he could've done differently to make things all right.

I've also done the 'character is lying to themselves' version, although the character was also an unmedicated schizophrenic so it was also supposed to partially represent disjointed thought patterns.

There are ways to use them. I don't know if you'd see them in published fiction, but they work fine in fanfic and anything where you can be a little more stylistic.