I tend to agree, though I'm not really an expert in that area. I suppose that it depends on the medication, the dose, and the symptoms, but I suspect that there are plenty of episodes where the medical community does little diagnosing and instead just prescribes the "relatively" harmless pills based on self-proclaimed depression.
That said, problems and diseases of the mind are considerably more elusive than those of the body - Mental illness is something that is hard to pinpoint, particularly with the inexact science (and a ton of psuedo-science) that exists in the field. If (and that's a big "if") the medication has a low level of side effects and it works for the majority of patients, then I'm not against prescribing it, provided the patient is informed as to the effects of the medication. Stronger medications, of course, require a much greater deal of care in administration.