The lungfish forum is there because there are numerous species of lungfish, and while there may not be very many posts, a lot of people keep them. There's no reason to dedicate a sub-forum to one species of fish. Not that many keep bowfin either, they're not readily available. Also, they're native fish. The ancient fish forum is only here because all of the fish in it fail to fall into any other categories.
And please, try not to be so defensive. The fact that you called lungfish "ugly" and used that as a criterion for why their sub-forum should be deleted is pretty flawed reasoning. Isn't being ugly a pretty good characteristic of being a monster fish? And let's be honest, bowfin may not be ugly but they're not exactly what most people would call nice-looking either. Even if they became popular, it doesn't mean they deserve a sub-forum. African tigerfish are very popular, and they're just lumped in with the other characins sub-forum.