Mod is simply the missions depot, the addons depot and the scripting depot all in one!
You've answered your own question, sniper_guy.
Why create another board/category when we already have 3 applicable boards there already?
Another reason is that mods usually have their own sites and their own forums, where they can break down the categories within their own mod.
To do so here is unpractical, as we either have to create another board that gets multiple threads per mod (see reason 1), or we create another category, and create a new board for each mod which is a very large drain on resources.
Alright, Ill just have to use ofp.info and opflashpoint.org instead...
Why not just create your own site & forums, wouldn't that be easier, and allow more freedom in how you want your mod to discuss things (especially in private)?
Worth thinking about.