It is still nuanced in how you do it. For example, what about age limits for drugs? What about adults being banned from getting drugs (say an 18 year old getting alcohol). What about pharmaceuticals being sold without a prescription. What about ensuring safety standards in what was being sold (say ensuring that the crack in the store wasn't cut with anything horrible).
Edit: That said, I do think the argument that even with all this, the argument that legalizing everything now and worrying about the details later is better than keeping it illegal while we work out details does have merit. I'm not convinced it is right, but I'm not convinced it is wrong either.