Maybe a term life insurance policy is too expensive. Maybe you have significant health problems and getting a typical insurance policy just isn’t feasible but you work in a high risk environment and want some financial protection if you are killed/injured.
These AD&D policies are more affordable, often do not require medical exam but also DO NOT typically offer as much in coverage as a Term policy would.
Often these are added on as “riders” to a traditional term policy when someone works in a high risk environment.
Also the nice thing about AD&D is that it covers dismemberment…not just death. If you are unable to work due to accident these policies will often pay out some if not all of the benefit.