I'm only speaking from intuition here, but I would say just taking the time to write an optional essay scores points. I don't think they expect it to be as impressive as your personal statement.
We can analyze our apps all day long, but...they're out there, and they're done. Just give yourself a pat on the back for the good work and don't stress too much over the details. Easier said than done, I know. I've gone over all my apps twice after submitting them.