Why would I attach things to a wiki?

The most common example of when you would attach something to a wiki would be when you need an image in the wiki page and you're concerned that if the image is hosted remotely (a corporate web server, for exampe), it might be moved or removed. Additionally, you might wish to attach a file to a wiki page if the attachment is only truly important in the context of the wiki page and therefore isn't important enough to be uploaded to the Document Manager of SourceForge.