Should people be allowed to be marijuana addicts?
The main concern I have regarding marijuana addiction is loss of productivity. It seems like if people weren't wasting all their time smoking (and "waste of time" behaviors while high) people could improve their life much more. The catch 22 seems to be that when sober humans they don't have the mental discipline to do what they want to do (or any similar explanation on why almost no people live up to their capabilities). Paradoxically, when high people often realize better what could be, yet they have less means (concentration + energy) to attain it. Personally I can't decide which way is better.
In common sense terms, you have laid it all out here — should people seek the relief they wish when life isn't perfect, even though they might change more things if they tried? From a legal/policy standpoint, we should let people seek whatever relief they want. From a clinical standpoint, we help people become all that they might be. And, overriding everything, we have to realize that people mainly fall short — to tell them all to get on with their lives is just a moralistic bromide.