Yes, it's definitely valuable. Although it's not a requirement to have a coordinator or wedding planner, a good coordinator helps to keep everything organized. They help to create a timeline that makes sense, and allows you to get all the photos that are necessary for your wedding day. When things don't happened perfectly as planned, it's nice to have someone (other than your family members or yourself) who can take care of any issues.
Typically when a coordinator is involved, weddings are stylized a little more, with colors, backdrops, and staging. This helps us produce even better pictures. For example, something as simple as having uplighting at the reception can really make a big difference in photography. It helps to create the mood.