This is how many forums are started. You want to attract people with similar interests. You then find out, low and behold, these folks have other interests as well that don't all mesh up so good. They start posting pictures of their big ugly camel on your pretty pony forum. It's amusing at first - people dig it and say stuff like "nice looking camel"; but then other camel people start coming out of the woodworks. Catastrophe is upon you, while you were looking the other way your pretty pony forum became a safe haven for spitting camel cameos. To avoid this unsavory scenario, the smart admin creates sub categories for people to share their various interests. These categories seldom, if ever, get larger than the primary one so there really is no need for a domain name change like you suggest. If it bothers you, you do have the option to bookmark just the forum(s) in which you're interested.