I think that one of the biggest reasons why it is not used in more mainstream therapy is that there is a belief that hypnosis does not work, and is nothing more than strangely packaged snake oil. Most universities do not teach hypnosis. So if they do not teach it, then why learn it. Second, a significant amount of people believe that hypnosis is a form of mind control. Even a popular Christian website, GotQuestions.org says that hypnosis is a form of demonic mind control. Probably, the biggest misconception is the question of whether or not I can be hypnotized. I tell everyone that there are only two types of people that can not be hypnotized. They are the ones that refuse, and the ones who are too developmentally and emotionally delayed to understand what I am saying. Everyone else can be hypnotized to some degree. Lastly, when someone is hypnotized, they do NOT feel any different, and at no point is control ever lost. Since all hypnosis is self-hypnosis, if any suggestion is given by the hypnotist that goes against person's will, the individual will either ignore the suggestion or instantly come out of hypnosis.
So what can hypnosis do?
Hypnosis is not the panacea of therapy. It is not the end all be all. However, it is only limited by the client's subconscious mind. Simply put, if the mind can conceive it, then it can become a part of a person's reality. To date, below is a sampling of what I seen accomplished with hypnosis.
Co-consciousness with D.I.D. Patients
Streff Syndrome Drastically Improved with D.I.D. Patients
Resolution of Trauma.
Learning hypnosis is simple. Therapists already do the majority of hypnosis by leading clients through a guided meditation or imagery. They thing which is missing is a few steps called convincers, inductions, deepeners, and finally anchors. To pick up these skills, do a simple YouTube search for hypnotists demonstrating the technique.