By default, the index itself has been uncollapsed and is already collapsible by clicking on a little icon (In the killing, it's the little box with a horizontal line on the top left of each category). The ability to collapse x category should be a default thing of forums(as far as I know, it is.) So putting in another code for the same purpose would be kinda....stupid?
And like what Hikaru/UnStellar said, leaving it uncollapsed in case someone spams the IC region would turn finding a specific topic a chore. It may take more space on the page, but it's easier to access when scrolling and finding a planet/territory you need to post in.
