Lack of Experience: Officiating a wedding is a serious task that involves legal and ceremonial responsibilities. Someone who isn’t experienced is most likely to struggle with the logistics and legalities involved in the process.
Emotional Involvement: A close friend or family member might be emotionally involved in your wedding, which could affect their ability to remain composed and focused during the ceremony.
Theological Knowledge: If you or your family have specific theological beliefs or traditions that need to be incorporated into the ceremony, a professional officiant or clergy member might be better equipped to handle this.
Legal Requirements: Most (if not all) jurisdictions in the US have legal requirements for who can officiate a wedding. A friend or family member might not meet these requirements, potentially leading to issues with the legality of your marriage. If a death occurs it would be a tremendous disaster to realize that your marriage is not valid.
Maintaining Relationships: Wedding ceremonies can be stressful, and if something goes wrong during the ceremony, it might strain your relationship with the friend or family member who officiated.
Balancing Roles: Balancing the roles of being a close friend or family member and an officiant can be challenging. It might be difficult for them to switch between these roles seamlessly.
Nothing makes the point better than this news article: Officiant fires gun to welcome bride, shoots grandson — and wedding goes on