Pain management. Indulging in morbid obsessions and curiosities is not uncommon among teens who are coming to terms with death and mortality. Some goth kids do hang out in cemeteries, yes. Does that mean they're being unhealthy? No, not necessarily.
Depression and friendships. Hanging out with other goth kids does not make it more likely for a teen to develop symptoms of depression. Rather, it can be helpful in terms of support and similar interests.
A dark attraction. It's not surprising that teens who struggle with depression are drawn to a darker subculture. OF course, not all kids who are depressed identify as goths.
The majority. The majority of teens who are depressed do not identify with any particular subculture, goth or otherwise. Many feel completely disenfranchised from the social scene altogether.
Social isolation. The social isolation faced by many teens is far more detrimental to their well-being than hanging out with a bunch of kids in black clothes with dark makeup on. Goths tend to at least identify with each other, rather than having no social identity whatsoever.
A method of protection. Goth kids can travel in packs and protect each other as any social group can. Goths also have fun and are allowed to smile and laugh, contrary to popular belief.
A healthy love of The Cure. A healthy love of The Cure and kohl eyeliner is nothing to worry about. Let the kids wear their spiked collars; it makes them happy and doesn't hurt anyone. Although..maybe spiked collars aren't the best examples of things that don't hurt anyone.