Outercourse is free, has no side effects, and can be a pleasurable way to have safer sex especially when no semen and vaginal fluids are exchanged.
For women, outercourse can be helpful to learn how to have orgasms. Many women don’t get orgasms from vaginal stimulation (or sexual intercourse) alone, but from clitoral stimulation. For men, outercourse allows them to be sexual without having the pressure to perform during sexual intercourse. So for couples, outercourse can be a great way to learn about each other’s bodies and give each other pleasure, without the worry of getting pregnant.