Once I've detoxed off drugs is rehab important?

Yes. Detox only helps to address the initial physical symtoms, but outpatient treatment is essential such as medications to allay craving, meetings and counseling to treat the reward and survival response of the brain. Addiction is a day to day disease that involves treatment from addiction specialists, counselors, therapists and the patient .It is a team effort.
YES. While detoxing may seem like the hardest part of drug addiction, staying clean is a bigger challenge. Rehab can help to teach you coping skills and remind you to stay out of situations where you may be tempted by drugs.