I swear I put a decent explanation on its filepage in a huge obnoxious yellow box so you can't miss it. Yes this image and box is very redundant, but it's for new editors to help the wiki out. To reword what is in the huge obnoxious yellow box, the purpose is to:

1) keep tables consistently sized (icytea's #ifexist for missing icons is something we've been messing around with)
2) enable users to easily upload images without getting too confused or making typos etc. I've seen lots and lots of confusion in my time of wiki editing. like this. Annnnnd countless others that have been deleted over time due to bad filenames. We need more editors, and well, we lose a lot of potential help because the wiki can be very confusing to new users. Especially when the wiki takes its sweet time updating itself to show new versions of old images. IMO the "DO NOT UPLOAD NEW IMAGES A BILLION TIMES" box should be a lot bigger, like really huge and obnoxious, like the boxes I've made.
3) it's supposed to look bad on the pages to encourage users to make it go away by uploading an image. It looks "better" than red text because of issue #1, but only slightly. The "looking bad" feel is similar to the doodle on the "Needs Updating" tag.
4) provide a more direct "missing files" method, there are lots of user and guild and misc. pages that are "missing" images that don't need to be called to editor attention.

Ah, by the by, we've greatly expanded on your wonderful category tree of "items providing blahblah defenses and status resistances." You should check it out!