Certainly, if you have a problem with your mood, whether caused by stress, chemical imbalance, etc., that is damping your productivity, then using a mood-altering drug can remove that damping effect and let your productivity return to an optimal level. This is different, though, I think, from "enhancing" productivity, which usually refers to things that can be used to move someone "beyond" the normal human optimal performance in some way.

What a part of me wants to say is, "the literature for returning humans to optimal mood is broad and well-researched, and shouldn't really be the topic of Amateur Medical-Advice Hour on a social news website; the best thing to do if you have a problem with your mood is to speak to a therapist/psychiatrist, who will recommend you a course of action based on current medical best practices." But...

I have to admit that that really isn't exactly true. Therapists and psychiatrists aren't required to have any more knowledge of neurochemistry than any other doctor; they'll be able to follow a guide and tell you that if you're depressed they should take you through cognitive behavioral therapy and prescribe you an SSRI (and then an SNRI if that doesn't work, and then a TCA if that doesn't work, &c) but they probably won't think about the serotonin production pathway and suggest that you might need more Vitamin B. This is one benefit of the internet: the people who are experts on their little staked claim of knowledge can give it to the people who seem to need it, instead of those people having to go around and talk to experts in all sorts of different fields to get the perspectives from those fields. On the other hand, it's pretty useless to give these pieces of advice to no-one in particular, without a specific problem at hand to solve. It's a bit like doing science without a hypothesis to test; everyone sees their own--more often than not false and overreaching--interpretation of the data.

The one good thing that does come out of these threads is that they tend to get more people to say "wait, that sounds like me, maybe I have [X mood disorder]," ask their doctors about it, and it turns out that they do. This is in stark contrast to usual hypochondria surrounding most diseases; where a person will be quick to diagnose themselves with [X cargo-cult symptom-matching thing-they-don't-understand] to explain why their neck always aches or they keep coughing up yellow phlegm, people are wary of assigning themselves mood disorders, since most people feel that society will still consider them "guilty" in some way for having the problem ["you're just lazy" &c], and they definitely don't want to bring it out in the open to the point where they identify with it. Discussions with a bunch of people chiming in to say "oh, yes, I thought I was [X fault-of-character], but really I just had [Y chemical imbalance] and some [drug] fixed it right up" can really push people to investigate this sort of thing where they otherwise wouldn't consider it.

I think the best compromise is that solutions should be discussed in the context of particular problems. Nootropics are an exception, because they don't solve any particular problem, other than the problem of wanting your life to be "even better-er"; but, for example, a root-level comment in this discussion about marijuana use really won't have anything good happen to it; each person will be looking at it in the context of a different problem and either implicitly accepting or rejecting the idea prima facie because of that. Better to ask a specific question, like "what drugs and/or therapies could be used to cope with stress-induced anxiety in the workplace"; then the discussion could actually go somewhere worth reading :)