As for the comment about medicating Barclay, by the Nth Degree episode he was functional enough that medication would do more to cause a dependency and prevent him from developing adjustment skills than to substantially help him with his issues. On the other hand by the 24th century they probably have more predictable medications that don't cause addiction and don't suddenly stop working.
Sort of my thought, medical technology has likely made dependency no longer an issue when it comes to medication, or at least any dependency can easily be countered by something akin to an ultra-rapid-detox technique, but without the consequences.
And as we see in this episode, before "infection" and later in "Realm of Fear" Barclay still has his various quirks and mannerisms, phobias and so forth. I'd still think something along the lines of medication would exist to allow him to function.