If there are these categories in the Singleplayer, then why not add it to the co-op?)

If you want to run those categories in coop, theres nothing stopping you, but its very unlikely that they will be added to the boards since there's little interest in those categories to begin with. We just went through a "purge" of a lot of the less popular category extensions a little while ago, since they had little to no activity. TUS or NMG co-op would likely suffer from the same issues.