I think the issue with providing a 'regular' health forum is that much of it revolves around self diagnosis and pharmaceuticals. My experience, at least, is that people who do more natural health are actually less likely to self diagnose. Tend to be more educated about health in general and their own personal health. Posting here would lead to too much potential for people to bypass doctors in favor of 'some guy online told me and he seemed like he really knew what he was talking about'.
Another issue is medication. Taking advice about medication from people who are not trained leads to a list of potential problems as well. And if people follow this advice and have negative results it may leave the site open for legal troubles since it was the site that provided a place for bad answers to be given.
These are just some of the possible reasons why i can see such ideas may not be in place. I'm not the site owner, so i have no power, just giving some things to think about. For all i know he may have plans for such things. But if it never shows, or to explain why it's not there now, those are some of the ideas i can see.
Far as the mental disorder, thats a wonderful concept, but spend a little time in the BDF (Bible Discussion Forum) and you will see how horrible this area would be. There are a number of people on this site who insist all mental health issues are actually demonic or even full on demonic possession. This forum would be nothing but a battle ground about that issue and little actual helpful information would ever get used and would only be more upsetting to people struggling than helpful.
Also take note, on this site, disclaimers are typically ignored because a large number of people on this site have a level of pride in themselves that makes them believe they are above the rules because they speak for God. Ironic how people like that always feel they are exempt from rules in the name of God.