In my workplace, "WED" is more than a word on a calendar page. It's a personal reminder: WRITE. EVERY. DAY. WED.
The surest way to become extraordinary at some skill is to practice it every day. That's how Derek Jeter, Mo'ne Davis, and Jimmie Johnson become legends in their sports. Jeter takes batting practice before every game. Johnson doesn't wait til race day to log hours at the wheel at 180 mph.
Writing is the same. Do it every day. You'll get better at it. Even if you're not writing a news release or a speech script. An actual letter to a friend will do. (Caveat: texts and emails don't count. Use paper and ink, not your thumbs. Your writing will have a greater sense of permanence, and you'll impress whomever receives your letter.)
Yes, we all know some PR people who don't write. They may be capable delegators. They may have great media relations skills. But they stumble when pressed to place words on paper, and if you've honed that skill, you'll be in constant demand. Because you'll be able to build relationships for yourself, your clients, and your co-workers -- based on the calibre of your prose.