Gurdur has an excellent post on "How not to criticize psychiatry". It's a must read.
Many psychomedications - just like many medications in general - can have bad side-effects. So do you for example recommend vaguely against antibiotics or cortisone or aspirin because in each case there can be bad side-effects? Or how about whether Lipitor (a statin, used to lower cholesterol level) can cause memory loss or not? Or chemotherapy meds that can really go to town in side-effects? This is yet again the hurdle of lack of exactness; a very vague accusation made without context or consideration. There is also the factor that a severe mental dysfunction is itself very dangerous to the sufferer - and as with many other conditions, such as the also-as-yet-poorly-understood autoimmune conditions, it becomes a matter of weighing risks and effects of a medication against risks and effects of the original illness.
Likely because like most people, most skeptics etc. simply don't know enough about psychiatry - or medicine in general. Access to good healthcare is an even more important issue, and includes psychiatry, yet just how many skeptics, atheists etc. cover health and healthcare issues in any detailed depth? Very few indeed. SC is right to say psychiatry should be a concern for the left, for skeptics, for everybody. But then so too should immunology, paediatrics, and practically every other branch of medicine. Health care is a pressing concern, and often very much a class issue too.