I'd never heard that advice before about keeping parentheses before, but you're right that it's immediately true why that's valuable wisdom. I think they're a device that's often overdone, as you say, but generally when I'm using them in my own writing, they're phrases that exude a ton of personality. There's also something to be said for clauses within em dashes, but that's another story lol.

Great piece, Janice!