The defination of a mental illness that I used, when working in that area, was any reaction to a given situation that caused a problem.
Homosexuality is not a mental illness. But being undualy distressed over it, for any reason, is.
The problem with mental illness is its association with a loss of reason. This loss of reason tends to create fear of loss of liberty.
There was a short horror story which was shown when I was still studying. A man was labeled as mentally ill. His protests were taken as evidence of his lack of insight. His distress was taken as evidence of depression and confusion. His anger was taken as evidence of his agitation and behavioural problems and so on. A number of associates were interviewed and encouraged to express their negative feelings toward this man. Just stop and think very carefully about everything you have done in the last few weeks, every person you've met. It's surprisingly easy to build a pretty convincing and self fulfilling case.
Mental illness is used frequently by politically motivated people. One of the most common is the label paranoia. In the West of Scotland and N Ireland, complaining about the Masons, for example, is generally labeled as paranois. The Masons there have a preverse influence that corrupts so much of society, but complaining about it, at least up to the early 90s was unadvisable.
In western societies, there is a generall acceptance of individualism. Expressing yourself as the opposite sex from your birth is, gradually becoming more accepted. Especially if, in the case of genetic men, you look fairly female. Genetic females, generally have more scope.
Moreover, western society is in a state of flux. Previous certainties, the church, have been dismissed. The last 400 years has seen various attempts to define new certaintities. 17th century, Protestantism, 18th century, capitalism, 19th century, imperialsm, 20th century (up to the 60s), cultural certainties. This has allowed each of us to define our own destinies. Within certain limits, we are able to express ourselves as we choose.
Gradually, mental ilness is being replaced as a means of social control by the notion of intelegence. Disagrement and dispute is said to be an example if limited intelegence. We, as a society must accept even preposterus notions, because these have been determined by experts. If we don't understand, it's because we lack the intelegence. If we openly disagree, it's because we have less intelegence than those who simply lack.
But, if we try to point anything out, that is conspiracy which means paranoia, which is mental illness.
So, there would appear to be some life in the mental illness industry yet.
Oh Woopee!