Think of therapy as somewhat of a placebo effect and why it's encouraged and believed to positively affect the patients mind because the patient wills it.

Regarding your examples, homosexuality and transsexuality were considered wrong up until we started defining mental illness as something that harms the patient in and of itself and their ability to function. For example homosexuality doesn't cause suicide, it's people's interpretation of it's sinfulness. Bipolar causes suicide in and of itself, doesn't matter how well accepted you are.

Homosexuals and transgendered individuals greatly benefit from therapy specifically tailored to help them cope. In fact you can't be approved for gender reassignment until you pass rigorous psychological screenings.

The expectation for bipolars is to learn to cope and re-invent how we interpret the world. It's also to help with the grieving and acceptance process. We can't snap out of a mood state but there is some self-awareness we are still capable of and that is what a good therapist should help you harness. They need to teach you how to restructure your life and assuage your guilt. If they are not--then you need a new therapist. If they talk about "mommy and daddy" too much then you need to find a new one. Therapists are a vast group of people. It's like saying "engineer". I still don't know what my brother means when he says that.

Therapy has proven to greatly benefit the mentally ill. My best therapist removed 40% of my PTSD after Seroquel removed the first 50%. She also tended to snap me out of a lot of my depression.

I think your expectation of therapy is too rigorous. It's a pseudo-science just like psychiatry except much easier to get into and more prevalent and encouraged. A good therapist won't know whether you are "regular" depressed or bipolar depressed. But it must have taken you years to figure that out yourself and you live in your head.

They are not authority figures or experts and that is my issue with therapy and how it's presented.

But is it good? Yes, if you find the type that works. In my case it's been REBT (one of the precursors to CBT) and for many bipolars it is DBT. It should be hard and unpleasant work at first and if it isn't then you're not in the right therapists office.