What I think would be very useful for new(er) users would be user-generated "upgrade" packages. Not just an "addon" that has to be installed by the user (which may involve manual modifying of .cfg files and the resulting "loss of interest" and frustration new users encounter doing this), but a complete "package" of sorts that can just be dropped in to an existing Orbiter installation, and works right from the get-go with no .cfg file alterations needed, etc.
Granted, this would require a "base" installation of Orbiter, and the "base" installation could vary from user to user (hi-res textures installed or not, etc), but it seems possible that it could be done.
For instance...an experienced user has an Orbiter installation for all the Space Shuttle addons, including the KSC hi-rez textures, hi-rez launch complexes, addon bases (Edwards, Vandenburg, etc), Shuttle Expansion Packs, etc. Couldn't they create a download of the entire package for the community so it could just be "dropped into" a base Orbiter installation?
The most frustrating thing about Orbiter for me is always trying to have to figure out what .cfg files need to be altered, etc, to get a conglomeration of separate addons to work with each other.
Maybe I'm just dreaming....
FalconAF