The tests are only to make sure that the addon is as authentic and ready for release as possible, so we dont have weapons on pylons that arent supposed to be there or UFO's (so far addons have been very good here). Also it was to catch weapons that have also been over modeled too. Its all about making online play with addons as simple as possible.
As for trying not to overstep someone else's project, well it will happen, and unfortunatly that means there will be 2 versions of an aircraft or weapon floating out there, meaning that it becomes twice as hard to use it online.
Another advantage is that the community would have a reference as to exactly who is working on what project, and based on those projects we could put out requests for data that normally wouldnt been seen in an addon, such as squadrons that fly with the plane, and tail numbers, which would add so much more depth to an addon.