We have provided an in-build Package utility under File->Package menu in FrameMaker 2015 which can be used to package all your files. But all the files should be under the root folder, otherwise it will not pick up your files in the package.
If your root folder of the book file contains all the files and then also some files are not picked up, then you can mail me the book file via dropbox at firstname.lastname@example.org to isolate the issue.
The images in all of our documents are stored in one central folder location, not under the individual documents. Numerous documents share the same images, so it would be foolish to copy the images in each document's directory. That would make it difficult to update the images in the future, and to find images for reuse. I can't imagine any professional tech comm group doing any different. The old Archive utility used to pull in all images files, regardless of their storage location. The new Package utility is useless in comparison. Please release an updated Archive script.
I have an ExtendScript script called ArchiveES that will do what you want. The cost is $19. Please contact me offlist if you are interested. Thanks. -Rick rick at frameexpert dot com
yes, the current 'package' function is pretty well useless.