You forgot profit, remember who will be making this Pharma grade MJ medicine
But it's not just about dosage and cost. it's a natural medicine in the form that I use it, I grow it and control what goes into it (and what doesn't), how and what I extract, mix it with in my coconut oil caps. I can't do that with any Pharma meds now, nor will I be able to with MJ-based Pharma meds. A lot of Pharma grade meds use natural extracts which have benefits in their natural state, but by the time Pharma gets through with it, they've added so many other things that you don't know what you're getting. in many cases they're likely reducing the positive effects of the natural product they started with.
Just like I use chamomile with a bud as a sleeping pill, both natural products dissolved in boiling water, plus it tastes good. I could be lazy like most people and get a script for some Pharma grade sleeping pills, but I choose not, always have, always will.