It might work if you hardlinked the directory containing the shared files into all your apps' workspaces (aka $HOMEs). I would just be worried about leaking privileges through the link somehow.
It also feels a lot like just recreating the original unified $HOME, and requires everything to be sorted by type. If you wanted to organize files by project and each project contained its own images, code, documentation, etc. then if you map the project directory for GIMP it can read all the files even though it should only get access to the images.