All insurance is unnecessary if you never have to use it. But when you need to use the insurance, it is important to have insurance that will actually take care of you. From the reports I read on SB, DAN will be there to take care of you, and is a very inexpensive way to have peace of mind in a diver's environment. Unfortunately, most people never read their "primary" insurance policies from the standpoint of the insurance carriers' lawyers, and do not understand what is really covered and what is not. Unfortunate surprises are not uncommon when people have to make a claim, but I do not recall anyone criticizing DAN's performance in diving accidents. I am not a DAN spokesperson, and have no vested interest in DAN, but do have their top tier dive insurance on all family members who dive.