Because I don't see any reason to keep it from us, other than anti-hacking purposes. Plus, it's there to click on, and anyone who clicks on it is going to start wondering what's in there.
And instead, I don't see any reason of why you have to do this useless polemic... Okay, I realize that it could have been kept hidden and visible only to moderators and administrators from the beginning, and I don't know why it hasn't never kept so... Probably, it was a choice of DjDecibel, that's it.
As I've written in the above post, it's just a forum section that the old website admins used to do tests and talk about this website and its forum, and it has used very little, actually. If you don't believe me and even begin to do stupid sort of conspiracy theories about it, well, it's just an your problem...
Same goes with real-world cases. In cases where information is kept secret from someone, they're likely to start asking questions to try and find out what that info is. That's why people are interested in government stuff, UFOs, etc.; it's because they want to know what's going on behind the scenes, and it's being kept from them, and this could potentially upset some people.
Oh my... Seriously?
It's jus the damn section of an Internet forum! Your exaggerated examples can't match it... Some people (but it's only you, so far...) can be "upset" because of a choice done by this forum ages ago? That's all? Who cares!
Why can't we upload txt files, 7-zip, or ar files? Also, the max upload size is a bit small, as MM2 screenshots could easily exceed that size if the resolution is set high enough.
Another question now... Are .txt files archives or images? No. Also, what's the purpose of giving the possibility to upload and download plain text files on this website? The .ar file aren't supported archive files, it's just MM2 that uses this file format for renamed .zip archives, and it's fine to put them in known official archive file formats to allow their downloading. It's alright about give the .7z files support, also if this format is still little used in general than .zip and .rar ones.
Also, you've gone a bit too much off-topic... I'm sorry for the new member who posted the topic, but you've now ruined it, congrats... Topic locked.