I agree that it must be frustrating to add a modification one of the members have created, and not have it work correctly or even at all. I've been frustrated myself while making changes and additions to my site so I can completely empathize with you.
I can't really speak officially for the site, that's for the Administration to do but, I can tell you my thoughts on the matter. This site is a development site, so you are going to see a lot of modifications that aren't going to always work and some that might work great but effect another modification, and make that one not work correctly. Even when an official vBulletin developer creates modifications it sometimes takes a while to work out all the bugs. We have coders that range from novice all the way to years of expertise. Some coders are better at getting the bugs out, updating files, and creating a professional experience; while others you have to search threw 10 pages to see that a bug was found and a fix given... or not find a fix at all because they gave up on coding.
So, while I can honestly say I've been in the same boat you are in I don't think any set of rules of organization of the projects will really help greatly. That's kind of the nature of things on a development site...
Thanks