Allows you to travel to areas you are not familiar with and ride a marked route without concern of getting lost or ending up in a section of town that will leave you practicing your sprints.

I do local organized rides to support the organizations that put them on. They are often the same organizations putting forth energy to create bike lanes and paths, doing driver/cyclist education, working with local owners of dogs that are quicker than my sprinting abilities, etc.

Many rides also are done for charity. So if it is a charity I like, it is a good way to support that charity.