Well I wouldn't do the optional essay just to make an excuse about your verbal score. If you are within the 80% range, you should really concentrate on other aspects of your application, b/c these are going to have to be slightly above average to help your cause. UCLA should give you descriptions of the type of things that should go in an optional essay. The question is do you have any of these "red flags" so to speak in your application? Just remember, this isn't a place to highlight your red flags, but to instead acknowledge them and continue to sell yourself. For instance, if you had an F in an undergraduate course, then address it, and talk about how much you learned and how it made you a better person, blah blah... Don't use the essay as an excuse b/c it will only point the adcome to the weakest part of your application. If your essays are perfect then they will know that your english/verbal is strong. Did you have to take the TOEFL? Then maybe that shows your strength. Have you considered taking the GMAT again? I think these are all questions you should ask yourself, but just remember, if you do decide to do the optional essay, KEEP SELLING YOURSELF. This isn't a time to put your tail between your legs and try to make excuses for poor performances. Hope this helps you decide
Just remember though, the quant portion of the test is more important, so your Q49 will be a bonus. The V30 is not horrible, so it might not evn be worth mentioning. I'm guessing the overall score was a 660?