A: Partially I blame direct marketing to the consumer.  But a large part of the problem is the pervasive tendency to treat symptoms instead of their drivers.  So the government insists that women over 60 should never take estrogen because it increases the risk for stroke.  This is untrue.  Only oral estrogens, which progressive doctors never use anymore, amplify the risk for strike.  The government promotes antidepressants for the treatment of menopausal symptoms instead, despite their scientifically reported tendency to increase stroke risk!  It make's one wonder who exactly is running the asylum. And too many consumers expect to be elated all the time & reject the normal ups & downs of life. Where is their moral fibre? 

A:  Because mind-based problems generally involve localized sets of highly compartmentalized molecules, small numbers of cell cohorts, isolated subsets of neurotransmitters and neurotransmitter receptors, &/or precisely specialized network connections.  Our knowledge & understanding even of the "normal" mind, although growing rapidly is still crudely limited.  And the psychoactive drugs currently at our disposal are far from selective, not being refined enough to exert the kind of selective, localized influences that would minimize unwanted side-effects.  These drugs are far too crude & invariant, doing far too much to too much brain tissue & doing it all the time, at full throttle, like the car whose cruise control mechanism is stuck on 100 kph.