Personally I think it’s a great way to value add to a deliverable by providing the build assets as well. Not all assets are fit to finish and require some work on the part of the end user and in some situations the build assets is a must have as to maintain the original fidelity of the asset.
That said more than a few marketplace assets included the source files, of note animations, and can be stored under the root tree, but not the content folder, so that the assets can be merged into the project with out adding the source files. So since it’s already done then the answer is yes you can add any information relative to the project files and documentation on more complex assets like blueprints is almost a must have.