A planning director may be involved in drafting one or two zoning ordinances in his or her entire career. There are consultants who prepare several zoning ordinances every year. Experience does count and the right consultant can bring a lot of experience to your project. Project requires objectivity. The community may need an objective evaluation of a complex situation that has become an emotional issue for people living in the community.
Project requires credibility.
There is some truth to the old adage that a consultant is someone from at least 50 miles away. Sometimes the community just needs the credibility of an outside expert, even if the planning staff and planning commission know what needs to be done.