I quite agree that the classification system is somewhat arbitrary. In no small part it's so that the forums can harmonise with the way the main website is divided, which is more a reflection of how to subdivide the religious texts of world traditions according to a more "classical" system of indexing.
This does of course create some problems with moving to a forum model. This is further complicated by the fact that it's generally not a good idea to create lots of empty boards, as much as create new boards where there is a specific need. For example, if there were a handful of regular posters with Ananda Marga backgrounds, you would almost certainly see a specific board for specific dialogue regarding that path.
Generally the divisions of the boards themselves can perhaps be best thought of as not a division of ideas, as much as a division of the technical languages of these followings. It's possibly not the best model, but as something that can incorporate the dynamic nature of the forum itself with the static nature of the main textual resources, it certainly can work.
However, of course, the forum is open to be shaped by its membership - ultimately it is a self-defining community. And if anyone feels a strong need for certain theme or topic boards, then I am happy to look into the matter.
All feedback is welcome.