The documented medicinal qualities are pretty lame, actually. Glaucoma? That's about it. As a pain reliever, it only has about 6,000 competitors, none of which have to be smoked for ingestion. It's 'medicinal effects' are touted not because it actually has any that are particularly remarkable, but because people want to be able to get it to toke up.
There will come a day, and probably in litigation-happy Californistan, when the wink-wink 'Pain relief' prescriptions backfire on the docs writing them now, after the long-term negative effects begin to take hold.