Even in our modern age, we know very little about how the brain works. This small amount of knowledge is consistently hyped up by overzealous scientists who all too often overstate their case. Much of it ends up "corroborating" essentialist ideas, particularly about gender. If the true defining factor of a working theory is its ability to predict (and thus affect, influence, and control), then neither social theory nor psychology have proven themselves worthy.
The psychological industry will claim to have improved many lives. It has also claimed lives. Most psychotherapy (psychotherapists, counselors, etc) are about as rigorous in methodology as a focus group or ethnography. There is the same general concern for researcher/subject power dynamics, superimposed upon therapist and patient. Thus, it is almost always useless to talk of some abstract, general idea of Psychotherapy, capital "P." Every psychotherapeutic interaction is intrinsically contextual, dependent upon the psychology of the specific individual therapist and specific individual patient. The same patient will get completely different results depending on the therapist, meanwhile the therapist is unlikely to achieve any consistent results among her patients. Thus, I am not against psychotherapy, per se. Psychotherapy has become an institution before it has proved itself effective, and it is important that any "revolutionary" brand of psychotherapy not repeat this mistake.
I'll leave a discussion of the pharmaceutical industry and its relation to psychology for another time...