I tell my students that parentheses are a whisper, a moment of intimacy between writer and reader. They build rapport; they signal trust. I love to use them (although I admit I forget their beautiful connecting power).
Parentheses make the reader feel included in a side conversation (I’m wondering if you feel closer to me right now). It’s an overlooked grammatical tool, one that affords a great moment of connection.
We’re writing essays to invite the reader into our minds, and parentheses, perhaps more than any other kind of writing maneuver, extend this invitation. I recommend inserting parentheses every once in a while to see how they feel (although I know it might feel awkward) and how they connect you again to your audience.