The very nature of dysfunction and sickness is highly culture-dependent. It is all a matter of statistics. If there is no dis-ease there is no disease. That the physical or mental state of a person CAN be different - does not imply that it MUST be different or even that it is desirable that it should be different. They adapt themselves to their environment and if the latter changes - they change.
Personality disorders are the best possible responses to abuse.
Cancer may be the best possible response to carcinogens. Aging and death are definitely the best possible response to over-population. Perhaps the point of view of the single patient is incommensurate with the point of view of his species - but this should not serve to obscure the issues and derail rational debate. It simply exists. WE, humans, introduce our value systems, prejudices and priorities into our activities, science included.