Why autonomy is considered a central component of the health care professional-patient relationship?

Because it reduces the risk and degree of responsibility that needs to be taken by the health care professional in the eyes of insurance company's. The fact is that a lot of patients do not have a clue nor will have as to the in and outs of their condition. Yet the doctor will give as little information as possible to avoid getting involved any more then is absolutely necessary. This is not always the case but it certainly more the rule then the exception.