There are also different tax and quantity rules around MMJ in Colorado. Medical card holders pay 2% (I think) tax while recreational pay over 20% tax. Medical card holders can also purchase 2oz at a time while recreational users can only buy an ounce at a time. Medical card holders can also grow twice the amount at home than non-card holders.
Until there's no differentiation between medical and recreational MJ, there will still be a need for doctors who are willing to fill out the paperwork for medical cards.